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1.
  • Andren, Henrik, et al. (författare)
  • Sources of mass bias and isotope ratio variation in multi-collector ICP-MS : optimization of instrumental parameters based on experimental observations
  • 2004
  • Ingår i: Journal of Analytical Atomic Spectrometry. - : Royal Society of Chemistry (RSC). - 0267-9477 .- 1364-5544. ; 19:9, s. 1217-1224
  • Tidskriftsartikel (refereegranskat)abstract
    • In this work, several contributing factors to the observed mass bias in inductively coupled plasma mass spectrometry (ICP-MS) have been identified. Analyses of the isotopic compositions of B deposited on sampler and skimmer cones demonstrate enrichment of [1][0]B on the former and [1][1]B on the latter. Grounding the capacitive discharge system to enhance sensitivity also magnified the level of [1][1]B enrichment on the skimmer cone more than four-fold. This supersonic expansion of the ion beam behind the sampler is confirmed to be an important source of mass bias. Isotopic analyses of the Fe, Zn and Ti leached from used extraction lenses yielded a linear relationship between the levels of lighter isotope depletion and mass ratio. Although consistent with the space-charge effect, the fact that isotopically-heavy deposits were found demonstrates that the ion beam diverges into a relatively wide solid angle in the field-free region behind the skimmer. This severely impairs transmission of, in particular, the lighter isotopes. For a wide range of elements (Li, B, Fe, Ni, Cu, Sb, Ce, Hf and Re), the magnitude of the mass bias was found to be affected by the sample gas flow rate, as well as the distance between the sampler and the end of the torch, i.e., the sampling depth, employed in the Neptune multi-collector ICP-MS instrument. Mathematical analysis of the profiles of intensity variations as a function of these instrumental parameters revealed that the response peaks closer to the torch for the heavier isotopes of all studied elements. Owing to this spatial non-coincidence, tuning for maximum intensity on either isotope will result in sampling from a region where even slight plasma instabilities will be translated into substantial variations in mass bias. Therefore, in-plasma processes also contribute to the degree and temporal stability of mass bias. In light of these findings, recommendations for optimizing multi-collector ICP-MS with respect to obtaining the highest possible precision are presented.
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2.
  • Appelblad, Petra K., et al. (författare)
  • The use of Pt guard electrode in inductively coupled plasma sectorÆeld mass spectrometry: advantages and limitations
  • 2000
  • Ingår i: Journal of Analytical Atomic Spectrometry. - : Royal Society of Chemistry (RSC). - 0267-9477 .- 1364-5544. ; 15:4, s. 359-364
  • Tidskriftsartikel (refereegranskat)abstract
    • Performance characteristics of inductively coupled plasma sector field mass spectrometry (ICP-SFMS) were studied with a Pt guard electrode (GE) inserted between the torch and load coil. The importance of the optimisation procedure and the matrix effects caused by a seawater matrix were assessed for 20 elements. Oxide and doubly charged ion formation was also investigated. Use of the GE allows a significant increase in ion transmission, by a factor of three to 20, thus resulting in improved instrumental detection limits. The improvement in sensitivity is mass dependent, with the highest gain observed for lower mass elements. Since, for the majority of analytical applications, actual detection limits depend upon blank levels rather on instrumental sensitivity, the most important factor for the determination of elements at ultra-trace levels is the degree of contamination of reagents and containers used. At the same time, significantly greater oxide formation is observed when operating the GE grounded rather than in the floating mode. For example, the BaO+/Ba+ ratio is ten to twelve times higher in the grounded mode. This calls for compromised instrumental parameters and the potential for severe spectral interferences from oxide species, which are often unresolved, even in high-resolution mode. Furthermore, non-spectral interferences from the seawater matrix appear to be more pronounced with the grounded GE, yielding a recovery of Ni of 55% compared with 93% in the floating GE mode. Hence all possible advantages and limitations of the use of the GE should be carefully considered prior to the analysis of real samples.
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3.
  • Appelblad, Petra, et al. (författare)
  • Model for calculating dead time and mass discrimination correction factors from inductively coupled plasma mass spectrometry calibration curves
  • 2000
  • Ingår i: Journal of Analytical Atomic Spectrometry. - : Royal Society of Chemistry (RSC). - 0267-9477 .- 1364-5544. ; 15:5, s. 557-560
  • Tidskriftsartikel (refereegranskat)abstract
    • A model allowing simultaneous determination of the detector dead time and the mass discrimination factor in inductively coupled plasma mass spectrometry (ICP-MS), as well as the corresponding uncertainties, is presented and compared for three representative isotope systems, namely magnesium, indium and thallium. The advantages of using the model presented are firstly that both the detector dead time and the mass discrimination factor can be obtained simultaneously and secondly that the sampling time can be spent entirely on the isotopes of interest.
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4.
  • Baxter, Douglas, et al. (författare)
  • Isotope abundance ratio measurements by inductively coupled plasma-sector field mass spectrometry
  • 2012
  • Ingår i: Journal of Analytical Atomic Spectrometry. - 0267-9477 .- 1364-5544. ; 27:8, s. 1355-1381
  • Tidskriftsartikel (refereegranskat)abstract
    • This tutorial reviews fundamental aspects of isotope abundance ratio measurement by inductively coupled plasma-sector field mass spectrometry (ICP-SFMS). After a synopsis of the scope of isotope abundance ratio measurement and a summary introduction to the factors affecting precision and accuracy, attention is turned to noise sources. Detailed theory behind Poisson or counting statistics and plasma flicker noise components is given, since much of the observed imprecision can be attributed to these sources. Using single collector instruments, ion beams from different isotopes are sampled in rapid sequence, and so ratioing of the signals will be subject to fluctuations derived from intensity variations, i.e., flicker noise. It is demonstrated that flicker noise can, under specified circumstances, become the limiting factor for the attainable precision. Furthermore, the practice of partitioning dwell times, ostensibly to optimize precision based on isotopic abundances and assumed Poisson statistics, is shown to be flawed and actually requires accounting for flicker noise. In addition to random uncertainty, various offset factors may contribute to systematic error in measured isotope abundance ratios. Two of these, namely mass scale shift and spectral interferences are ameliorated using ICP-SFMS. The former is eliminated when operating under conditions providing flat-topped peaks, such that the minor drift in mass calibration typical of the technique becomes inconsequential and the intensity remains the same. Isotope abundance ratio measurements are subject to three further important offset factors. First is abundance sensitivity, which quantifies the extent of peak tailing to neighboring masses and can present a considerable source of offset. Second is mass bias, resulting from the fact that all sector field devices exhibit increasing sensitivity with ion mass, and various empirical methods used to correct for this effect are compared and contrasted. Third is detector dead time, which affects mass spectrometers equipped with ion counting systems. Although a well-understood phenomenon, all current methods for determining the dead time on the basis of experimentally measured isotope abundance ratios are likely to yield biased estimates. Finally, the capabilities of ICP-SFMS for the determination of isotope abundance ratios are placed in perspective by making a brief comparison with other techniques.
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5.
  • Baxter, Douglas, et al. (författare)
  • Revised exponential model for mass bias correction using an internal standard for isotope abundance ratio measurements by multi-collector inductively coupled plasma mass spectrometry
  • 2006
  • Ingår i: Journal of Analytical Atomic Spectrometry. - : Royal Society of Chemistry (RSC). - 0267-9477 .- 1364-5544. ; 21:4, s. 427-430
  • Tidskriftsartikel (refereegranskat)abstract
    • An internal standard (IS) can be used to account for moderate, matrix-related shifts in mass bias using multi-collector inductively coupled plasma mass spectrometry through the empirical, linear relationship between measured isotope abundance ratios for different elements in ln-ln space. Unfortunately, erroneous mass bias corrected isotope abundance ratios may be returned by the model, requiring artificial adjustment of the true isotope abundance ratio of the IS. Although inadequate correction for peak tailing has been convincingly used to explain this problem, our analysis of the literature describing the development of the mass bias correction model using an IS reveals the presence of a source of systematic error. The origin of this error is purely mathematical and is eliminated in the revised model presented, in which mass bias corrected isotope abundance ratios are independent of the isotopic composition of the IS. An expression for computing the total combined uncertainty in the corrected ratio, incorporating contributions from the linear model, the isotopic reference material, and measurements of analyte element and IS in the sample, is also derived.
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6.
  • Björn, Erik, et al. (författare)
  • Calibration errors due to variations in peak characteristics in the measurement of transient signals by inductively coupled plasma-scanning mass spectrometry
  • 2002
  • Ingår i: Journal of Analytical Atomic Spectrometry. - 0267-9477 .- 1364-5544. ; 17:12, s. 1582-1588
  • Tidskriftsartikel (refereegranskat)abstract
    • The impact of variations in peak characteristics on the fidelity of transient signal measurement by inductively coupled plasma-quadrupole mass spectrometry (ICP-QMS) was investigated. Specifically, the question as to whether the multi-element capabilities or the accuracy in determined analyte amounts were deteriorated compared to what has been reported previously when not considering peak variations was addressed. The peak characteristics considered were the time of the signal maximum (tpeak), the standard deviation of the assumed Gaussian input function generated by the sample introduction system (σG), and the time constant for signal decay (τ). Investigations of simulated exponentially-modified Gaussian peaks revealed that, for variations of peak characteristics within reasonable ranges, measurement noise and variations in tpeak, σG and τ all contributed to calibration uncertainty. Electrothermal vaporisation (ETV) and flow injection (FI) systems were used to experimentally generate transient signals of varying peak characteristics. Removing data points from the raw signals simulated the monitoring of up to 100 mass-to-charge ratios, allowing calibration data and analyte amounts to be determined from the processed signals. To obtain calibration graph slopes with relative standard deviations below 1% for the ETV-ICP-QMS system, it was found necessary to acquire 7-24 data points per peak for 50-5 ms dwell times. On this basis, the maximum number of mass-to-charge ratios that could be monitored in a typical ETV-ICP-QMS analysis was 4-10 using dwell times of 50-5 ms. With the FI-ICP-QMS system, variations in the peak characteristics between calibration standards and samples meant that, to obtain less than 3% error in determined analyte amounts, at least 7 or 10 points per peak were required for external and internal standardisation, respectively. It was found that variations in peak characteristics contributed more than measurement noise to the error in determined analyte amounts. In recent studies it has been reported that 3-4 data points per peak are sufficient to accurately monitor a transient if peak variations are not considered, which, for typical ETV signals, would allow the monitoring of 20 mass-to-charge ratios during a single measurement cycle. Thus the results obtained here show that the multi-element capability of ICP-QMS when monitoring transient signals can be severely compromised by such variations.
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7.
  • Björn, Erik, et al. (författare)
  • Calibration errors due to variations in peak characteristics in the measurement of transient signals by inductively coupled plasma-scanning mass spectrometry
  • 2002
  • Ingår i: Journal of Analytical Atomic Spectrometry. - : Royal Society of Chemistry (RSC). ; 17, s. 1582-8
  • Tidskriftsartikel (refereegranskat)abstract
    • The impact of variations in peak characteristics on the fidelity of transient signal measurement by inductively coupled plasma-quadrupole mass spectrometry (ICP-QMS) was investigated. Specifically, the question as to whether the multi-element capabilities or the accuracy in determined analyte amounts were deteriorated compared to what has been reported previously when not considering peak variations was addressed. The peak characteristics considered were the time of the signal maximum (tpeak), the standard deviation of the assumed Gaussian input function generated by the sample introduction system (G), and the time constant for signal decay (). Investigations of simulated exponentially-modified Gaussian peaks revealed that, for variations of peak characteristics within reasonable ranges, measurement noise and variations in tpeak, G and all contributed to calibration uncertainty. Electrothermal vaporisation (ETV) and flow injection (FI) systems were used to experimentally generate transient signals of varying peak characteristics. Removing data points from the raw signals simulated the monitoring of up to 100 mass-to-charge ratios, allowing calibration data and analyte amounts to be determined from the processed signals. To obtain calibration graph slopes with relative standard deviations below 1% for the ETV-ICP-QMS system, it was found necessary to acquire 7–24 data points per peak for 50–5 ms dwell times. On this basis, the maximum number of mass-to-charge ratios that could be monitored in a typical ETV-ICP-QMS analysis was 4–10 using dwell times of 50–5 ms. With the FI-ICP-QMS system, variations in the peak characteristics between calibration standards and samples meant that, to obtain less than 3% error in determined analyte amounts, at least 7 or 10 points per peak were required for external and internal standardisation, respectively. It was found that variations in peak characteristics contributed more than measurement noise to the error in determined analyte amounts. In recent studies it has been reported that 3–4 data points per peak are sufficient to accurately monitor a transient if peak variations are not considered, which, for typical ETV signals, would allow the monitoring of 20 mass-to-charge ratios during a single measurement cycle. Thus the results obtained here show that the multi-element capability of ICP-QMS when monitoring transient signals can be severely compromised by such variations.
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8.
  • Björn, Erik, et al. (författare)
  • Non-spectral interference effects in inductively coupled plasma mass spectrometry using direct injection high efficiency and microconcentric nebulisation
  • 2001
  • Ingår i: JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY. - : Royal Society of Chemistry (RSC). ; 16, s. 4-11
  • Tidskriftsartikel (refereegranskat)abstract
    • Non-spectral interference effects in inductively coupled plasma mass spectrometry (ICP-MS) were investigated for the direct injection high efficiency nebuliser (DIHEN) the large bore DIHEN (LB-DIHEN) and a microconcentric nebuliser (MCN) with a cyclone spray chamber. Interference effects from nitric and sulfuric acid, methanol and sodium nitrate solutions were studied. Eight elements with different ionisation potentials (IP) and atomic masses were monitored at various nebuliser gas flow rates. The processes giving rise to interference effects observed with the DIHEN were investigated by monitoring relative analyte sensitivities at different radial plasma positions. It was found that the average magnitude of interference effects decreased in the order MCN approximate to DIHEN > LB-DIHEN, showing that analytical performance is improved by removing the spray chamber. It is suggested that remaining interference effects observed for the DIHEN are caused by a matrix induced spatial redistribution of the aerosol in the plasma due to differences in droplet. size distribution and density between water and the matrix solutions. In addition, the high plasma solvent load with the DIHEN results in a pronounced negative correlation between relative analyte signal magnitude and IP. For the LB-DIHEN, these effects were smaller, and other element specific interference effects dominated. For the eight elements monitored, element specific interference effects increased in the order MCN < DIHEN < LB-DIHEN. Transient acid effects were also investigated and found to be virtually eliminated by the use of a DIHEN instead of the MCN system. For the latter, stabilisation times of 3-10 mill were necessary when changing the nitric acid concentration between 0.22 and 2.2 mol 1(-1).
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9.
  • Blachucki, Wojciech, et al. (författare)
  • A laboratory-based double X-ray spectrometer for simultaneous X-ray emission and X-ray absorption studies
  • 2019
  • Ingår i: Journal of Analytical Atomic Spectrometry. - : Royal Society of Chemistry. - 0267-9477 .- 1364-5544. ; 34:7, s. 1409-1415
  • Tidskriftsartikel (refereegranskat)abstract
    • X-ray spectroscopy studies are usually performed using synchrotron radiation sources, which offer bright, coherent, energy-tuneable and monochromatic light. However, the application of synchrotron-based Xray emission spectroscopy (XES) and X-ray absorption spectroscopy (XAS) is directly constrained by the limited, infrequent access to central facilities. With the advent of new technological solutions in the field of X-ray sources, optics and detectors, the development of efficient and compact laboratory X-ray spectroscopy systems is possible. A permanent laboratory-based setup offers the advantages of low cost and easy accessibility and, therefore, more flexibility in the preparation and scheduling of measurements. Herein, we report a laboratory X-ray setup allowing simultaneous XES and XAS measurements. The double von Hamos spectrometer performances are demonstrated by concurrent K beta XES and K-edge XAS measurements done for 3d elements.
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10.
  • Bredberg, Anna, et al. (författare)
  • Analysis of manganese and iron in exhaled endogenous particles
  • 2014
  • Ingår i: Journal of Analytical Atomic Spectrometry. - 0267-9477 .- 1364-5544. ; 29, s. 730-735
  • Tidskriftsartikel (refereegranskat)abstract
    • Background: Many full-time welders experience some sort of respiratory disorder e.g., asthma, bronchitis and metal fume fever. Thus, welding aerosols are thought to cause airway inflammation. There is a need for markers of welding aerosols in exposure assessments, and as most welding aerosols contain manganese and iron, these metals may possibly be used as an indicator. We have previously developed a novel non-invasive technique to collect endogenous particles in exhaled air (PEx). This study is designed to i) develop a method for analysis of manganese and iron in PEx and ii) investigate whether the manganese and/or iron content of PEx changes after exposure to welding aerosols. Methods: Nine individuals were experimentally exposed to welding fumes. PEx was collected at three time points for each individual; before, after and 24 hour after exposure. Analyses of PEx samples were performed using Inductively Coupled Plasma Mass Spectrometry (ICP-MS). Results: Four out of nine individuals showed an increase in manganese and iron levels after exposure to welding aerosols. The mean manganese and iron concentration increased from,
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11.
  • Clayton, R, et al. (författare)
  • Precise determination of the isotopic composition of Sn using MC-ICP-MS
  • 2002
  • Ingår i: Journal of Analytical Atomic Spectrometry. - : Royal Society of Chemistry (RSC). - 1364-5544 .- 0267-9477. ; 17:10, s. 1248-1256
  • Tidskriftsartikel (refereegranskat)abstract
    • High precision isotopic measurements of Sn in two commercially available high purity materials and a previously analysed cassiterite from Straits Settlement, Malaysia, are presented as a basis for a new measurement procedure using the Micromass IsoProbe MC-ICP-MS. The results show that under optimised instrumental conditions two laboratory calibration standard solutions (Johnson-Matthey Puratronic Grade 1 Sn metal foil and Specpure ICP/DCP Sn solution) are isotopically identical and an external reproducibility of 0.000017 2 s. d. at 150 ppb Sn concentration (Sn-122/Sn-116 0.318597, n = 14) can be achieved. An isotopic fractionation of +0.13parts per thousand/ u (1.3 epsilon units) relative to these in-house standards has been verified for the cassiterite, which indicates a natural isotopic fractionation of approximately 2.8 times greater than the long-term reproducibility of the current optimised measurement procedure.
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12.
  • Cornelis, Geert, 1978, et al. (författare)
  • A signal deconvolution method to discriminate smaller nanoparticles in single particle ICP-MS
  • 2014
  • Ingår i: Journal of Analytical Atomic Spectrometry. - : Royal Society of Chemistry (RSC). - 0267-9477. ; 29:1, s. 134-144
  • Tidskriftsartikel (refereegranskat)abstract
    • Single particle ICP-MS (spICP-MS) analysis of inorganic nanoparticles (NPs) cannot accurately distinguish dissolved ion signals and signals from relatively small NPs, although these particles are often more reactive than their larger counterparts. A signal deconvolution method was developed for spICP-MS analysis using gold (Au) NPs of nominally 10, 15 or 30 nm diameter. The signal distributions of dissolved Au standards were parameterised as a function of concentration using a mixed Polyagaussian probability mass function. Dissolved curves were fitted using this parameterisation to the low-intensity signals of samples containing NPs to subtract and deconvolute the dissolved signals from the particle signals. The dissolved signals were quantified in this process. The accuracy of the deconvolution method was confirmed for all NP suspensions studied when comparing the size and number concentration obtained with the deconvolution method with values based on transmission electron microscopy. This method thus allows analysis of NP suspensions with spICP-MS where it was hitherto not possible. The applicability domain lies predominantly with relatively small NPs and/or when a relatively high concentration of dissolved ions of the element of interest is present, where overlapping between dissolved and particulate signals occurs.
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13.
  • Daun, Charlotte, et al. (författare)
  • Separation of soluble selenium compounds in muscle from seven animal species using size exclusion chromatography and inductively coupled plasma mass spectrometry
  • 2004
  • Ingår i: Journal of Analytical Atomic Spectrometry. - : Royal Society of Chemistry (RSC). - 1364-5544. ; 19:1, s. 129-134
  • Tidskriftsartikel (refereegranskat)abstract
    • To study the role of selenium compounds for the quality and nutritional value of meat, speciation of selenium compounds was performed in two muscles from each of seven animal species (chicken, turkey, duck, ostrich, lamb, cattle and pig). Soluble selenium compounds were separated by size-exclusion chromatography (SEC) and detected by inductively coupled plasma-mass spectrometry (ICP-MS). Four selenium peaks were found in the muscle extracts by SEC, with partition coefficients (K-av) of 0.02, 0.44, 0.74 and 0.86, respectively. The second and third peaks had a chromatographic mobility approximately corresponding to that of tetrameric glutathione peroxidase and selenoprotein W, respectively, and they contained 68-100% of the recovered selenium in different muscles. The distribution of selenium among the four peaks varied considerably in muscles from different species, the second peak accounting for 28-71% of the recovered selenium and the third peak for 17-72%. These differences in selenium distribution among animal species are discussed in relation to meat quality and nutritional value.
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14.
  • Dowlatshahi Pour, Masoumeh, 1976, et al. (författare)
  • Mass spectrometry imaging as a novel approach to measure hippocampal zinc
  • 2019
  • Ingår i: Journal of Analytical Atomic Spectrometry. - : Royal Society of Chemistry (RSC). - 0267-9477 .- 1364-5544. ; 34:8, s. 1581-1587
  • Tidskriftsartikel (refereegranskat)abstract
    • Zinc (Zn2+) is an essential trace element that plays crucial roles in the functioning of hundreds of enzymes and DNA binding transcription factors. Zinc is also an essential neuromodulator and can act as a potent neurotoxin in excitotoxic brain injury after seizures, strokes, and brain trauma where high levels of Zn2+ can cause irreparable brain damage in certain brain regions. However, the mechanism of neurotoxicity has not been fully understood yet and is still under debate. In the present study, we have developed a time of flight secondary ion mass spectrometry (ToF-SIMS) imaging method to investigate the distribution of zinc in the rat brain. The zinc distribution in hippocampus sections from healthy rats and rats exposed to traumatic brain injury was imaged and the results were compared to those from conventional zinc-probe based fluorescence microscopy. Two related zinc species, ZnOH3 + and ZnO2H+, can successfully be visualized by ToF-SIMS in the rat hippocampus. Statistical data analysis of the image data demonstrated a substantial increase of both ZnOH3 + and ZnO2H+ in the zinc related species in the acute brain injury tissue. Our findings positively support the fact that toxic vesicular zinc accumulation might not be the sole source for neuronal degeneration following traumatic brain injuries. Also, we could successfully apply ToF-SIMS imaging for the first time to visualize the zinc content and distribution across hippocampus sections. Consequently, ToF-SIMS is a powerful method to further investigate biological phenomena such as seizures, ischemia, and strokes and also other forms of cellular damage in the central nervous system.
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15.
  • Dubascoux, S., et al. (författare)
  • Field-flow fractionation and inductively coupled plasma mass spectrometer coupling: History, development and applications
  • 2010
  • Ingår i: Journal of Analytical Atomic Spectrometry. - : Royal Society of Chemistry (RSC). - 0267-9477 .- 1364-5544. ; 25, s. 613-623
  • Tidskriftsartikel (refereegranskat)abstract
    • Field-Flow Fractionation (FFF) is now recognised as a versatile pool of techniques allowing particle size or molar mass to be obtained in a wide variety of samples covering numerous applications in the fields of environment, materials or biology. In the same time, Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) has an indisputable place in the field of elemental detectors and the coupling between FFF and ICP-MS can be considered as an emerging technique capable to reach relevant physico-chemical information at sub-micrometre scale and trace element concentration level. This paper gives some key elements of FFF-based fractionation linking theory and practical analytical aspects, from injection and preconcentration to analysis. The different components of the coupling are described. Summary tables of the main operating conditions of FFF-ICP-MS coupling are presented and operating conditions such as carrier composition, flow and nebulizers are discussed. Special attention is given to the FFF-ICP-MS interface. Qualitative and quantitative analysis is also discussed. Applications in the fields of environment, bioanalysis and nanoparticles are presented in order to illustrate the potentialities of such coupling.
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16.
  • Elsayed, Moneim, et al. (författare)
  • Optimisation of operating parameters for simultaneous multi-element determination of antimony, arsenic, bismuth and selenium by hydride generation, graphite atomiser sequestration atomic absorption spectrometry
  • 2000
  • Ingår i: JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY. - : Royal Society of Chemistry (RSC). ; 15:6, s. 697-703
  • Tidskriftsartikel (refereegranskat)abstract
    • Hydride generation, sequestration in graphite tubes and simultaneous multi-element measurement by atomic absorption spectrometry were used for determination of Sb(V), Bi(III), Se(IV), As(III) and As(V) in Millipore or brackish water by a method based on batchwise addition of the samples to a reaction vessel. As the reducing agent, NaBH4 was added at a controlled flow rate. A statistical programme, Modde 4.0, capable of multivariate optimisation of working parameters for the multi-element determination, was used to optimise the concentrations of HCl, the amount of NaBH4, purge gas flow rates, the graphite atomiser's deposition temperature, as well as the temperature of the reaction vessel.In general, the concentrations of HCl and the amount of NaBH4 had the greatest impact on the response and several of the working parameters showed interactions. For highest sensitivity different parameters had to be used for the two matrices. Optimum parameter settings in Millipore and brackish water were: concentration of HCl 2.1 and 2.7 mol l(-1), respectively; 2% NaBH4 addition during 120 s (4 ml) or 84 s (2.8 ml), respectively; Ar purge gas flow rate 150 ml min(-1) in both matrices; reaction vessel temperature 16 and 0 degrees C, respectively; and a deposition temperature of 600 and 150 degrees C, respectively. The detection limits were restricted by variations in the blank absorbance. For 2 ml of sample the detection limits in brackish water were 17, 14, 25 and 140 ng l(-1) for As, Se(IV), Bi and Sb, respectively.
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17.
  • Enger, Jonas, et al. (författare)
  • Direct detection of antimony in environmental and biological samples at trace concentrations by laser-induced fluorescence in graphite furnace with an intensified charge coupled device
  • 1995
  • Ingår i: Journal of Analytical Atomic Spectrometry. - : Royal Society of Chemistry. - 0267-9477 .- 1364-5544. ; 10:8, s. 539-549
  • Tidskriftsartikel (refereegranskat)abstract
    • The technique of laser-induced fluorescence in graphite furnace (LIF-GF) with intensified charge coupled device (ICCD) detection was used for the detection of Sb at pg ml-1 concentrations in various biological and environmental samples. The ICCD detector permits the simultaneous multichannel detection of large fluorescence wavelength regions, which gives the user the possibility to control and correct for various background signals (which is important when complex environmental and biological samples are to be analysed). The detection limit for Sb in a pure water solution was found to be 5 fg. Antimony was directly detected in pure aqueous solutions down to fg ml-1 concentrations. A variety of aqueous and solid environmental and biological samples were investigated with respect to their Sb content. Good agreement between the measured and certified Sb contents (at pg ml-1 - ng ml-1 levels) was obtained for various certified reference materials, viz., marine sediments (MESS-1 and BCSS-1) and riverine water (SLRS-2). Measurements of the Sb content in non-certified natural drinking water, estuarine water reference material (SLEW-1), serum reference material (Seronorm), and whole blood of healthy Swedish people were also performed. After a thorough investigation and elimination of various sources of contamination (regarding sampling and sample storage), typical levels of Sb in human whole blood at or below several tens of pg ml-1 were obtained. These levels are significantly lower than previously established values of the normal Sb content in human blood. The detection limit for Sb in human whole blood was close to that of pure water.
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18.
  • Engström, Emma, et al. (författare)
  • Effects of sample preparation and calibration strategy on accuracy and precision in the multi-elemental analysis of soil by sector field ICP-MS
  • 2004
  • Ingår i: Journal of Analytical Atomic Spectrometry. - : Royal Society of Chemistry (RSC). - 0267-9477 .- 1364-5544. ; 19, s. 858-866
  • Tidskriftsartikel (refereegranskat)abstract
    • Soil samples were prepared for multi-element analysis using HNO3 leaching or pseudo-total digestion with HNO3, HCl and HF in a microwave oven, both methods requiring 70 min heating time. Two calibration approaches for the soil characterization were also compared: external calibration, combined with internal standardization, and isotope dilution (ID) after appropriate spiking of the soils with a stable isotope mixture prior to sample preparation. Analyses were performed using inductively coupled plasma sector field mass spectrometry (ICP-SFMS). Accurate total elemental concentrations were only obtained for Cd and P using both sample preparation methods in two certified reference materials, NIST SRM 2709 and CCRMP SO-2, as well as comparable values for a Finnish inter-laboratory soil. The pseudo-total digestion method also provided accurate results for As, Be, Co, Fe, Mn, Ni, Pb, Sb, Ti, V and Zn. For Cu in SO-2 and Cr in both certified reference materials, incomplete recoveries were always obtained. In the case of Cr, this is due to difficulties associated with the complete solubilization of refractory minerals.For a given final dilution factor, external calibration provides better limits of detection (LODs) than ID. As both methods of quantification yield results of essentially equivalent accuracy and precision, external calibration is to be preferred as a greater number of elements are amenable to analysis in a shorter measurement time. On the other hand, ID can be combined with matrix separation (NH3 precipitation was used here), allowing lower dilution factors to be used without deleterious effects on the instrumental performance. In particular, improved LODs could be obtained for Cd, Cu and Hg, primarily as a result of being able to introduce ten-fold more concentrated solutions from which the bulk of the matrix had been removed. For Cu and Ni, matrix separation almost eliminated Ti, and thus the formation of spectrally interfering TiO+ was completely suppressed. Potentially, the combination of ID and matrix separation would allow these elements to be determined without resorting to medium resolution measurement mode, again improving the LODs for the determination by ID-ICP-SFMS.
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21.
  • Forsgård, Niklas, et al. (författare)
  • Accelerator mass spectrometry in the attomolar concentration range for C-14-labeled biologically active compounds in complex matrixes
  • 2010
  • Ingår i: Journal of Analytical Atomic Spectrometry. - : Royal Society of Chemistry (RSC). - 0267-9477 .- 1364-5544. ; 25:1, s. 74-78
  • Tidskriftsartikel (refereegranskat)abstract
    • Accelerator mass spectrometry (AMS) is an ultra-sensitive analytical method suitable for detection of sub-nanomolar concentrations of labeled biological substances such as pharmaceutical drugs in body fluids. A limiting factor in extending the concentration measurements to the sub-picomolar range is the natural C-14 content in living tissues. This can be circumvented by separating the labeled drug from the tissue matrix with, for example, liquid chromatography. The analysis of drugs and their metabolites or endogenous compounds in biological fluids by liquid chromatography is usually complicated and the sample preparation step remains the most serious problem both with regard to losses and degradation of the analyte, and also automation of the analysis. In this article a method for detection and quantification of extremely low concentrations of C-14-labeled biomolecules in biological fluids by AMS is described. The use of a column switched chromatographic system incorporating a restricted-access media (RAM) column allowed the direct injection of untreated human plasma samples, which reduces the total time of analysis and makes automation of the sample preparation step possible. As the separated total drug amount is in the attogram to femtogram region, it is not possible to use a standard AMS sample preparation method, where mg sizes are required. We have utilized a sensitive carbon carrier method where a C-14-deficient compound is added to the HPLC fractions and the composite sample is prepared and analysed by AMS. The method shows remarkable sensitivity, low background values and good linearity, allowing the detection and quantification of a pharmaceutical drug in human plasma in the low femtomolar and down to the attomolar concentration range.
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22.
  • Goitom, Daniel, et al. (författare)
  • Comparison of aerosol properties and ICP-MS analytical performance of the Vulkan direct injection nebuliser and the Direct Injection High Efficiency Nebuliser
  • 2007
  • Ingår i: Journal of Analytical Atomic Spectrometry. - : Royal Society of Chemistry (RSC). ; 22, s. 250-7
  • Tidskriftsartikel (refereegranskat)abstract
    • Monodisperse polymer particles consisting of DVB and styrene-copoly-DVB were successfully synthesized by photoinitiated precipitation polymerization with 2,2'-azobis(2-methylpropionitrile) (AIBN) as initiator. A focused 150 W xenon short arc lamp was used to radiate the sample mixtures. The size of the particles ranged from 1.5 to 4 m and could be varied by changing the monomer concentration between 2 and 10% (v/v) and by means of the time of polymerization. By using photoinitiation instead of thermal initiation, it was possible to avoid coagulum and arrive at spherical particles with an exceptionally high monodispersity for particles of this size range (polydispersity index < 1.02) and with monomer loadings well above 5%.
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23.
  • Goitom, Daniel, et al. (författare)
  • Noise characteristics and analytical precision of inductively coupled plasma mass spectrometry using a Vulkan direct injection nebuliser for sample introduction
  • 2006
  • Ingår i: Journal of Analytical Atomic Spectrometry. - London : Royal Society of Chemistry. - 0267-9477 .- 1364-5544. ; 22:2, s. 168-176
  • Tidskriftsartikel (refereegranskat)abstract
    • Noise and precision of ion count rate measurements were characterised for ICP-MS using a Vulkan direct injection nebuliser (Vulkan DIN) for sample introduction. For comparison, experiments were also carried out using a direct injection high efficiency nebuliser (DIHEN). The Vulkan DIN gave considerably higher relative white noise compared with the DIHEN, −40.3 compared with −45.8 dB, and measurements of aerosol characteristics showed that this was a result of broader size distribution and larger mean size of droplets for the Vulkan DIN. At a liquid flow rate of 85 μL min−1, the aerosol volume fraction constituted by droplets with a diameter smaller than 10 μm was only 5% for the Vulkan DIN compared to 38% for the DIHEN, and the Sauter mean diameter was 30.2 and 11.1 μm, respectively. Compared with the DIHEN, interference noise from a peristaltic pump was very small with the Vulkan DIN because at the liquid flow rate giving maximum sensitivity, the analyte signal intensity was not much affected by changes in liquid flow rate. Although this had a positive effect on precision, it indicated that the plasma is cooled by large droplets that do not positively contribute to the analyte signal intensity. For analytical precision data it was evident that with the Vulkan DIN, precision was limited by the high white noise in the frequency range 0.4–500 Hz, but for the DIHEN there were relatively large contributions from 1/f and/or interference noise to the observed precision. When using integration times of 1000 ms or longer, the DIHEN did, however, appear to give slightly better precision for most of the isotopes tested. For comparison, precision data was also generated when using a conventional spray chamber sample introduction system and it was found that, with a 3000 ms integration time, both direct injection nebulisers gave better precision for most isotopes. Although analytical precision is impressive, the results in this paper also show that both direct injection nebulisers produce aerosols that are far from ideal for the types of ICPs currently used in commercial instruments.
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24.
  • Goitom, Daniel, et al. (författare)
  • Radial ICP characteristics for ICP-AES using direct injection or microconcentric nebulisation
  • 2005
  • Ingår i: Journal of Analytical Atomic Spectrometry. - London : Royal Society of Chemistry. - 0267-9477 .- 1364-5544. ; 20:7, s. 645-651
  • Tidskriftsartikel (refereegranskat)abstract
    • Radial analyte signal intensities, fundamental plasma parameters, and non-spectral interference effects were characterized for inductively coupled plasma atomic emission spectrometry (ICP-AES) using a direct injection nebuliser (Vulkan DIN) or a microconcentric nebuliser (MCN) coupled to a cyclonic spray chamber for sample introduction. Radial analyte signal intensity profiles for atomic and ionic lines with energy sum (Esum) between 1.85 and 15.41 eV were used. When using the MCN system, for all lines the signal intensity profiles were parabolic with maxima at the axial centre of the plasma. For the Vulkan DIN, the shapes of the profiles were dependent on their Esum showing minimum intensities at the axial centre of the plasma for lines with high Esum values. The ionisation temperature, electron number density and magnesium ion-atom line intensity ratio determined indicated that ionisation and excitation capabilities were deteriorated at the centre of the plasma when using the Vulkan DIN compared with the MCN. This was found to be not simply a result of high aerosol load when using the Vulkan DIN, but because of poor plasma–aerosol interaction, possibly caused by the confined distribution of aerosol in the plasma and high nebuliser gas velocity. Indeed, for the Vulkan DIN, electron number density and ionisation temperature increased with liquid flow rate, which could be explained by plasma shrinkage, or the thermal pinch effect, which increased the aerosol–plasma interaction at increased liquid flow rates. As a consequence, when increasing the liquid flow rate in the range 20–90 µL min–1: (i) analyte sensitivity increased linearly; (ii) the plasma became unstable; (iii) the magnitude of matrix effects remained almost unaffected. These results are partly in contrast to observations made with other types of direct injection nebulisers and ICP instruments.  
  •  
25.
  • Grasse, Patricia, et al. (författare)
  • GEOTRACES inter-calibration of the stable silicon isotope composition of dissolved silicic acid in seawater
  • 2017
  • Ingår i: Journal of Analytical Atomic Spectrometry. - : Royal Society of Chemistry (RSC). - 0267-9477 .- 1364-5544. ; 32:3, s. 562-578
  • Tidskriftsartikel (refereegranskat)abstract
    • The first inter-calibration study of the stable silicon isotope composition of dissolved silicic acid in seawater, delta Si-30(OH)(4), is presented as a contribution to the international GEOTRACES program. Eleven laboratories from seven countries analyzed two seawater samples from the North Pacific subtropical gyre (Station ALOHA) collected at 300 m and at 1000 m water depth. Sampling depths were chosen to obtain samples with a relatively low (9 mmol L-1, 300 m) and a relatively high (113 mmol L-1, 1000 m) silicic acid concentration as sample preparation differs for low- and highconcentration samples. Data for the 1000 m water sample were not normally distributed so the median is used to represent the central tendency for the two samples. Median delta Si-30(OH)(4) values of +1.66& for the low-concentration sample and +1.25& for the high-concentration sample were obtained. Agreement among laboratories is overall considered very good; however, small but statistically significant differences among the mean isotope values obtained by different laboratories were detected, likely reflecting inter-laboratory differences in chemical preparation including pre-concentration and purification methods together with different volumes of seawater analyzed, and the use of different mass spectrometers including the Neptune MC-ICP-MS (Thermo Fisher (TM), Germany), the Nu Plasma MC-ICP-MS (Nu Instruments (TM), Wrexham, UK), and the Finnigan (TM) (now Thermo Fisher (TM), Germany) MAT 252 IRMS. Future studies analyzing delta Si-30(OH)(4) in seawater should also analyze and report values for these same two reference waters in order to facilitate comparison of data generated among and within laboratories over time.
  •  
26.
  • Hogmalm, Johan, 1979, et al. (författare)
  • In situ Rb-Sr and K-Ca dating by LA-ICP-MS/MS: an evaluation of N2O and SF6 as reaction gases
  • 2017
  • Ingår i: Journal of Analytical Atomic Spectrometry. - : Royal Society of Chemistry (RSC). - 0267-9477 .- 1364-5544. ; 32:2, s. 305-313
  • Tidskriftsartikel (refereegranskat)abstract
    • In situ dating of K-rich minerals, e.g. micas and K-feldspar, by the Rb–Sr isotopic system is a new development made possible by the ICP-MS/MS technique. Online chemical separation of Rb and Sr is possible in an O2-filled reaction cell, wherein a portion of the Sr reacts to SrO+ while simultaneously no RbO+ is formed. O2 reactions provide stable analytical conditions sufficient for precise and accurate determination of Rb/Sr and Sr/Sr isotopic ratios using 80 micron laser ablation spots. However, to date <10% of the Sr reacts with O2 as reaction gas, leaving room for improvement using more potent reaction gases. With a more efficient reactive transfer, it should be possible to obtain similar results with a smaller laser spot size, hence gaining higher spatial resolution. In this study, we have evaluated N2O and SF6 as reaction gases since they have previously been shown to react strongly with Sr+, without affecting Rb+. Analytical conditions, including cell parameters and reaction gas flow rate were optimized while ablating NIST SRM 610. The main reaction product is SrO+ for N2O reaction and SrF+ for SF6 reaction. Both gases show significantly higher reaction product formation compared to O2 with >85% of Sr reacting with N2O and >70% Sr reacting with SF6; Rb does not react with either gas. As a result, the sensitivity for Sr reaction products is ∼10 times higher with N2O and ∼8 times higher with SF6 compared to O2. With these more reactive gases, the error of mica isochron ages, calibrated against a newly developed nano-particulate pressed powder tablet of mica–Mg, is ∼1% using a 50 μm laser spot. Our tests show that both N2O and SF6 form interfering reaction products, e.g., SrOH (N2O), SiF3 and TiF3 (SF6) that are difficult to handle using single mass spectrometer instruments, but which can be overcome using MS/MS. Using SF6 combined with H2, it is possible to measure 40Ca+ as 40Ca19F+, free from interference of 40Ar+ and 40K+. This facilitates the dating of micas by the K–Ca isotopic system; we present the first in situ K–Ca age determination.
  •  
27.
  • Hogmalm, Johan K., et al. (författare)
  • In situ Rb–Sr and K–Ca dating by LA-ICP-MS/MS: an evaluation of N2O and SF6 as reaction gases
  • 2017
  • Ingår i: Journal of Analytical Atomic Spectrometry. - 0267-9477 .- 1364-5544. ; 32, s. 305-313
  • Tidskriftsartikel (refereegranskat)abstract
    • In situ dating of K-rich minerals, e.g. micas and K-feldspar, by the Rb–Sr isotopic system is a new development made possible by the ICP-MS/MS technique. Online chemical separation of Rb and Sr is possible in an O2-filled reaction cell, wherein a portion of the Sr reacts to SrO+ while simultaneously no RbO+ is formed. O2 reactions provide stable analytical conditions sufficient for precise and accurate determination of Rb/Sr and Sr/Sr isotopic ratios using 80 micron laser ablation spots. However, to date <10% of the Sr reacts with O2 as reaction gas, leaving room for improvement using more potent reaction gases. With a more efficient reactive transfer, it should be possible to obtain similar results with a smaller laser spot size, hence gaining higher spatial resolution. In this study, we have evaluated N2O and SF6 as reaction gases since they have previously been shown to react strongly with Sr+, without affecting Rb+. Analytical conditions, including cell parameters and reaction gas flow rate were optimized while ablating NIST SRM 610. The main reaction product is SrO+ for N2O reaction and SrF+ for SF6 reaction. Both gases show significantly higher reaction product formation compared to O2 with >85% of Sr reacting with N2O and >70% Sr reacting with SF6; Rb does not react with either gas. As a result, the sensitivity for Sr reaction products is ∼10 times higher with N2O and ∼8 times higher with SF6 compared to O2. With these more reactive gases, the error of mica isochron ages, calibrated against a newly developed nano-particulate pressed powder tablet of mica–Mg, is ∼1% using a 50 μm laser spot. Our tests show that both N2O and SF6 form interfering reaction products, e.g., SrOH (N2O), SiF3 and TiF3 (SF6) that are difficult to handle using single mass spectrometer instruments, but which can be overcome using MS/MS. Using SF6 combined with H2, it is possible to measure 40Ca+ as 40Ca19F+, free from interference of 40Ar+ and 40K+. This facilitates the dating of micas by the K–Ca isotopic system; we present the first in situ K–Ca age determination.
  •  
28.
  • Korvela, Marcus, et al. (författare)
  • Internal standards in inductively coupled plasma mass spectrometry using kinetic energy discrimination and dynamic reaction cells
  • 2018
  • Ingår i: Journal of Analytical Atomic Spectrometry. - : ROYAL SOC CHEMISTRY. - 0267-9477 .- 1364-5544. ; 33:10, s. 1770-1776
  • Tidskriftsartikel (refereegranskat)abstract
    • ICP-MS is a sensitive element analysis technique used for analyzing several different sample types. This can result in difficult matrixes which can affect both physical parameters and create overlaps of analyte elements. Some of the possible overlaps can be reduced by the use of reaction and/or collision cells, while the use of internal standards can help with reducing the physical interferences caused by a matrix. While both internal standardization and the use of cells have been studied separately, their effects on each other have not been investigated earlier. In this study ICP-MS was used to analyze Mg-24, Al-27, Ti-47, Ti-49, V-51, Cr-52, Cr-53, Mn-55, Fe-57, Co-59, Ni-60, Ni-61, Ni-62, Cu-63, Cu-65, Zn-66, Zn-67, As-75, Se-78, Se-82, Cd-111, and Pb-208 with Be-9, Y-89, Ga-69, Rh-103, In-115, Ir-193, and Tl-205 as internal standards with high concentrations of either HNO3, PBS-buffer, or Triton X-100 as the matrix, in reaction-, collision- and standard-cell modes. This was done to investigate which internal standards would compensate matrix effects in different cell modes. All internal standards, except Be, compensated fairly well (relative sensitivity RSD < 10%) even for severe matrix effects for most elements regardless of similarity in mass in the different cell modes. For Zn, As and Se no proper internal standard could be found, of the ones investigated.
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29.
  • Kumar, Sunil J., et al. (författare)
  • A simple method for synthesis of organotin species to investigate extraction procedures in sediments by isotope dilution-gas chromatography-inductively coupled plasma mass spectrometry : Part 2. Phenyltin species
  • 2004
  • Ingår i: Journal of Analytical Atomic Spectrometry. - London : Royal Society of Chemistry. - 0267-9477 .- 1364-5544. ; 19:3, s. 368-372
  • Tidskriftsartikel (refereegranskat)abstract
    • A rapid method for the synthesis of phenyltin species based on the phenylation of tin iodide was developed and a standard of 124Sn, enriched monophenyltin (MPhT), diphenyltin (DPhT) and triphenyltin (TPhT) was produced. Isotope enriched species were added to and equilibrated with the certified reference material BCR 646 to evaluate different extraction procedures currently in use for the determination of organic tin species in sediments. Samples were measured by gas chromatography-inductively coupled plasma mass spectrometry (GC-ICP-MS) with species specific isotope dilution (SSID) calibration. For TPhT measurement results agreed with the certified values for extraction methods using tropolone in diethyl ether alone or in the presence of NaCl and HCl as well as with 50% HBr. However, with 50% HBr, concentrations obtained for DPhT and MPhT were above the upper limit (2) of the certification. The stability of phenyltin species was studied by comparing their signal magnitudes in spike solutions generated directly after derivatisation with those obtained after applying the extraction–derivatisation procedures. Degradation of phenyltin species was matrix dependent and appeared for most of the extraction methods investigated. For water standards and BCR 646, extraction with methanol combined with dichloromethane or methanol combined with acetic acid gave no degradation when applied with less than 20 min ultrasonication. Extraction efficiencies for these two methods were however low for the BCR 646 matrix, in particular for DPhT and MPhT.
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30.
  • Kumar, Sunil Jai, et al. (författare)
  • A simple method for synthesis of organotin species to investigate extraction procedures in sediments by isotope dilution gas chromatography-inductively coupled plasma mass spectrometry : Part 1. Butyltin species
  • 2003
  • Ingår i: Journal of Analytical Atomic Spectrometry. - : Royal Society of Chemistry (RSC). - 0267-9477 .- 1364-5544. ; 18:714-9
  • Tidskriftsartikel (refereegranskat)abstract
    • A method for the synthesis of butyltin species, based on the butylation of tin iodide in diethyl ether, was developed. A standard of 116Sn enriched monobutyltin (MBT), dibutyltin (DBT), tributyltin (TBT) and tetrabutyltin (TeBT) was produced and used as a spike for isotope dilution gas chromatography-inductively coupled plasma mass spectrometry. Isotope enriched species were added to and equilibrated with certified reference sediments NRC PACS-2 and BCR 646 to evaluate different extraction procedures currently used for the determination of butyltins in sediments. Measurement results agreed with certified values for TBT, DBT and MBT for the certified reference materials, using extraction methods with acetic acid–methanol or 50% HBr. Poorer results were obtained for extractions using the complexing agent tropolone in diethylether or a methanol/dichloromethane mixture, or with sequential extractions including tropolone in diethyl ether and NaCl in hydrochloric acid. The TeBT spike was used to investigate the extraction efficiencies of the species. For the method involving 50% HBr the extraction efficiencies were found to be 102% for TBT, 85% for DBT and 27% for MBT. Although the calculated efficiencies were low for MBT, when extracting with 50% HBr recoveries of 97% for BCR 646 and 110% for PACS-2 were obtained with species-specific isotope dilution calibration.
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31.
  • Kvashnina, Kristina O., et al. (författare)
  • Direct study of the f-electron configuration in lanthanide systems
  • 2011
  • Ingår i: Journal of Analytical Atomic Spectrometry. - : Royal Society of Chemistry (RSC). - 0267-9477 .- 1364-5544. ; 26:6, s. 1265-1272
  • Tidskriftsartikel (refereegranskat)abstract
    • The valence shell electron configurations within a few electron volts above the Fermi level in cerium, ytterbium, europium and samarium compounds were probed by resonant X-ray emission spectroscopy (RXES) at the L-3 absorption pre-edge. The rare earth systems show distinct spectral signatures depending on the f-electron configuration. The high energy resolution experimental results reported here are well reproduced by atomic multiplet calculations confirming the localized character of the 4f electrons. The magnitude of the electron-electron interactions within the 4f shell and between 3d and 4f electrons is analyzed. The present technique is a powerful tool for the study of the 4f valence electron configuration that, unlike L-3 absorption spectroscopy at the main edge, is little influenced by valence electron relaxation following core hole creation.
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32.
  • Larsson, Tom, et al. (författare)
  • Species specific isotope dilution with on line derivatisation for determination of gaseous mercury species
  • 2005
  • Ingår i: Journal of Analytical Atomic Spectrometry. - : RCS Publishing. - 0267-9477 .- 1364-5544. ; 20:11, s. 1232-1239
  • Tidskriftsartikel (refereegranskat)abstract
    • A species specific isotope dilution (SSID) method for determination of the volatile mercury (Hg) species Hg0, (CH3)2Hg, CH3HgX and HgX2(where X is a counter ion) in gaseous samples was developed. The procedure involved on line derivatisation of ionic Hg species with sodium tetraethylborate during sampling, before collection of species on a Tenax TA tube in series with an Au–Pt tube. Collected species were thermally desorbed and determined by GC-ICP-MS. The procedure provided absolute detection limits of 0.5 pg for CH3HgX and (CH3)2Hg, 5 pg for HgX2 and 25 pg for Hg0. Recoveries and transformations of the investigated species were studied for the different procedural steps and the method was tested for microcosm experiments on brackish water sediment samples, as well as for laboratory air samples. As a result of methylation and reduction processes within the sediment, gaseous emission rates could be determined for all investigated species after addition of an isotope enriched aqueous inorganic 199Hg2+ standard to the sediment. Hg0 was the only specie detected in laboratory air samples (4.5 ng m–3). The procedure for derivatisation of ionic Hg species prior to collection on Tenax TA reduces memory effects and transformations of CH3HgX and HgX2, which is especially advantageous at low sample gas flow rates and for complex gaseous matrices, such as emissions from sediment samples. SSID provides simplified methodological development, as well as efficient correction for matrix induced losses and transformations of Hg species. The method could be useful for various biogeochemical studies of Hg, as well as for reliable risk assessments during, for example, waste management and soil remediation.
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33.
  • Liao, Xin, et al. (författare)
  • Allanite U–Th–Pb geochronology by ion microprobe
  • 2020
  • Ingår i: Journal of Analytical Atomic Spectrometry. - : The Royal Society of Chemistry. - 0267-9477 .- 1364-5544. ; 35:3, s. 489-497
  • Tidskriftsartikel (refereegranskat)abstract
    • Allanite, an epidote group mineral, occurs as a common accessory mineral in igneous, metamorphic rocks and hydrothermal deposits. It contains radioactive elements Th and U, making it a valuable U–Th–Pb geochronometer for various geological processes. Due to the structural and compositional complexity of allanite, in situ dating method is a better choice when the allanite is heterogeneous or has crystallized in multi-stage events. The wide variation of chemical compositions, however, raises the potential for matrix effects and complicates the use of in situ methods for allanite U–Th–Pb chronology. To address this issue, we made a comprehensive investigation on allanite U–Th–Pb chronology using Secondary Ion Mass Spectrometry (SIMS). Five allanite samples (CAP, Daibosatsu, SQ-51, Toba OTT, TARA allanite) with variable elemental compositions and common lead concentrations have been used. Allanites with variations in FeO (from 12.8 to 16.1 wt%) and similar ThO2 contents (around 1–2%) do not show significant matrix effects, as suggested by a previous study. While, obvious changes in calibration parameters (UO2+/U+, ThO2+/Th+) were noticed for allanites with a large range of Th contents (from 300 ppm to 2.0 wt%). By employing power law relationships between Pb+/U+versus UO2+/U+, Pb+/Th+versus ThO2+/Th+ with suitable exponentials, we do not observe obvious matrix effects with ThO2 concentrations variations. This study demonstrates that allanite can be a good geochronometer for multi-stage mineralization of hydrothermal deposits, providing valuable complementary information to zircon and monazite.
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34.
  • Lindahl, Patric, et al. (författare)
  • Performance and optimisation of triple quadrupole ICP-MS for accurate measurement of uranium isotopic ratios
  • 2021
  • Ingår i: Journal of Analytical Atomic Spectrometry. - : Royal Society of Chemistry. - 0267-9477 .- 1364-5544. ; 36:10, s. 2164-2172
  • Tidskriftsartikel (refereegranskat)abstract
    • The performance characteristics of the Agilent 8900 triple quadrupole inductively coupled plasma mass spectrometry (ICP-MS/MS) system were evaluated and optimised concerning stability in measurements of uranium isotopic ratios. Multiple measurement parameters were evaluated for the determination of U isotopic ratios in certified standard solutions containing U-233, U-235 and U-238. Large irregular biases during repeated measurements of U isotopic ratios were observed using two identical ICP-MS/MS instruments. Depending on the mass filter resolution settings, the accuracy of U isotopic ratios can deviate up to 100% from the certified reference value. These variations in U isotopic ratios are primarily recognised as irregular drifts in the mass calibration of the two mass filters. This mass calibration drift is dependent on the isotope mass with a more pronounced drift for heavier isotopes. In order to solve the problem the resolution settings were optimised for both mass filters, which resulted in considerable improvement in precision and accuracy. A precision of 0.07% (relative standard deviation) for long-term measurement of U-233/U-235 ratios was achieved. Mass bias corrected U isotopic ratios agree very well with certified reference values with overall relative deviations from reference values of 0.005% and 0.17% for the SQ mode and MS/MS mode, respectively. The impact of the first mass filter in the MS/MS mode has a significant effect on the mass bias discrimination process and hence the accuracy of U isotopic ratios.
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35.
  • Majidi, Vahid, et al. (författare)
  • Improving sensitivity for CE-ICP-MS using multicapillary parallel separation
  • 1999
  • Ingår i: Journal of Analytical Atomic Spectrometry. - : Royal Society of Chemistry (RSC). - 0267-9477 .- 1364-5544. ; 14:12, s. 1933-1935
  • Tidskriftsartikel (refereegranskat)abstract
    • A multicapillary, capillary electrophoresis inductively coupled plasma mass spectrometry interface is described. This interface allows for higher sample loading to improve the overall sensitivity and analyte detection limits without sacrificing the separation efficiencies. The results obtained with this parallel system are presented for a cross flow nebulizer. A comparison of single capillary electrophoresis for both DIHEN and cross flow nebulizers is presented.
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36.
  • Malinovskiy, Dmitry, et al. (författare)
  • Performance of high resolution MC-ICP-MS for Fe isotope ratio measurements in sedimentary geological materials
  • 2003
  • Ingår i: Journal of Analytical Atomic Spectrometry. - 0267-9477 .- 1364-5544. ; 18:7, s. 687-695
  • Tidskriftsartikel (refereegranskat)abstract
    • High resolution MC-ICP-MS is used for the precise measurement of variations in the isotopic composition of Fe in ferromanganese concretions and sediments relative to IRMM-014 standard. The sensitivity for 56Fe in high resolution mode was 3 V per mg lm1 Fe, a figure that is comparable to those from other MC-ICP-MS instruments operated at low resolution. Incorporation of a guard electrode and the efficient ion transmission capabilities of the Neptune MC-ICP-MS instrument are responsible for the high sensitivity. It was observed that the use of HCl resulted in the formation of ClOH+, causing interference with 54Fe in particular. This acid has been preferred in some cases over HNO3 to minimize formation of ArN+, the major interferent for 54Fe. Using the high resolution mode of the Neptune, the nature of spectral interferences is unimportant as all are completely resolved and will not affect the accuracy of the determined Fe isotope ratios. As the instrument also provides flat-topped peaks, high resolution operation does not necessarily result in impaired precision, providing that higher concentrations are used to compensate for the loss in sensitivity compared with the low resolution mode. In the present work, external reproducibilities of 56Fe/54Fe and 57Fe/54Fe isotope ratios were better than 50 ppm (one standard deviation) at a concentration of 5 mg lm1. The level of instrumental mass discrimination observed for raw ratios drifted by as much as 0.09% per mass unit over a measurement session, but could be corrected on-line by simultaneous monitoring of the 62Ni/60Ni isotope ratio. Variations in the Fe concentrations or the acid strength of measurement solutions were found to affect the apparent mass discrimination. Increasing the Fe concentration caused a relative decrease in the raw 56Fe/54Fe and 57Fe/54Fe isotope ratios, thus ruling out the space charge effect as the explanation for this phenomenon. Instead, it is suggested that the larger dry aerosol particles formed at higher Fe concentrations are not completely vaporized until later in the plasma, thus reducing the relative rate of diffusional losses of lighter 54Fe from the central channel. However, application of on-line correction using Ni could adequately account for this effect. From the results for a variety of sedimentary geological materials, analysis of three-isotope data revealed that equilibrium fractionation of Fe occurred during deposition. To be able to distinguish between equilibrium and kinetic fractionation processes, it is imperative to collect accurate and precise data for the 56Fe/54Fe and 57Fe/54Fe isotope ratios. These requirements are readily fulfilled by applying high resolution MC-ICP-MS and on-line correction for instrumental mass discrimination using Ni.
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37.
  • Mason, P.R.D., et al. (författare)
  • In situ determination of sulfur isotopes in sulfur-rich materials by laser ablation multiple-collector inductively coupled plasma mass spectrometry (LA-MC-ICP-MS)
  • 2006
  • Ingår i: JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY. - : Royal Society of Chemistry (RSC). - 0267-9477. ; 21:2, s. 177-186
  • Tidskriftsartikel (refereegranskat)abstract
    • A new method has been developed for the accurate and precise measurement of sulfur isotopes (S-32, S-33, S-34) in solids on a scale down to 80-100 pin by laser ablation multiple collector inductively coupled plasma mass spectrometry (LA-MC-ICP-MS). The method was developed independently on two different sets of instrumentation, both of which give equivalent results with comparable accuracy and precision. The first instrumental set-up utilizes Xe gas in a hexapole collision and reaction cell for interference attenuation coupled with a mass discrimination correction by external normalization using a nebulised vapour of Cl-37/Cl-35 standard solution. The second employs high mass resolution by sector field mass spectrometry to avoid the interfering O2+ isobars with a Si-30/Si-29 standard aerosol for external normalization. The external isotope mass discrimination correction was applied using the exponential law and was further calibrated for both sets of instrumentation by linear interpolation in a sample-standard bracketing method. Mean delta(34)S(V-CDT) and delta(33)S(V-CDT) show excellent agreement (within analytical error, typically 0.6 and 1.5%, respectively) with compiled data for IAEA-S series AgS standard reference materials. Results for NIST SRM 127 (sulfate) were less accurate when calibrated against the IAEA-S series sulfides, whilst significant and consistent deviations in accuracy of up to 3%. were observed in both sets of instrumentation for Soufre de Lacq SRM sulfur. Such generic matrix effects may be widespread in LA-ICP-MS due to differential ablation rates, particle formation, particle transport efficiency and ionization efficiency in an argon plasma.
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38.
  • Nguyen Van, Dong, et al. (författare)
  • A comparison between continuum- and line source AAS for speciation analysis of butyl- and phenyltin compounds
  • 2006
  • Ingår i: Journal of Analytical Atomic Spectrometry. - London : Royal Society of Chemistry. - 0267-9477 .- 1364-5544. ; 21:7, s. 708-711
  • Tidskriftsartikel (refereegranskat)abstract
    • The analytical potential of using instrumentation based on AAS for speciation analysis was investigated. Organic tin (OT) species were determined following gas chromatographic (GC) separation, atomization in a quartz tube (QT) and detection by line source AAS (LSAAS) and, for comparison, by state of the art continuum source AAS (CSAAS). For an unbiased comparison of the AAS instruments, their working conditions were individually optimized. For CSAAS, the linear range was limited by the GC column capacity (10-1600 ng g-1) and for LSAAS this range was limited by stray radiation (20-1000 ng g-1). With background correction, the instrumental LODs for OT were 6-22 pg as tin for CSAAS, while for LSAAS corresponding values were five to ten times poorer. Without background correction, the LOD of CSAAS was twice as good as that of LSAAS. For method validation, two certified reference materials, Harbour Sediment BCR-646 and Oyster Tissue BCR-710, were analysed.
  •  
39.
  • Nguyen Van, Dong, et al. (författare)
  • Redistribution reactions of butyl- and phenyltin species during storage in methanol
  • 2005
  • Ingår i: Journal of Analytical Atomic Spectrometry. - : Royal Society of Chemistry (RSC). - 0267-9477 .- 1364-5544. ; 20, s. 266-72
  • Tidskriftsartikel (refereegranskat)abstract
    • The stability of organotin species, which are frequently used as standards, in methanol has been investigated by gas chromatography coupled to either quartz furnace atomic absorption spectrometry, inductively coupled plasma mass spectrometry or mass spectrometry. Ethylation with sodium tetraethylborate was used during sample preparation. The species composition of single or mixed standard solutions at a concentration of 10 µg g–1 was investigated after storing at –20 °C, +4 °C and +22 °C for various time periods. All butyltin species (monobutyltin—MBT, dibutyltin—DBT and tributyltin—TBT) were found to be stable for all storage conditions, even when mixed. The single triphenyltin (TPhT) standard was also stable, whereas mono-and diphenyltin (MPhT; DPhT) were unstable. MPhT redistributed to DPhT and inorganic tin (IOT), while DPhT redistributed to MPhT and to a minor extent to TPhT. In a mixture containing MBT, DBT, TBT, MPhT, DPhT and TPhT, besides the above mentioned reactions, DPhT was found to react strongly with MBT forming up to 73% monobutyl-monophenyltin (MBMPhT) and MPhT. The composition of MBMPhT was investigated by GC-MS. Suggestions for the type of reactions leading to the redistribution of OT species are outlined and suggestions on how to prepare stable OT standards are made.
  •  
40.
  • Nygren, Ulrika, et al. (författare)
  • Lanthanide phosphate interferences in actinide determination using inductively coupled plasma mass spectrometry
  • 2005
  • Ingår i: Journal of Analytical Atomic Spectrometry. - 0267-9477 .- 1364-5544. ; 20:6, s. 529-534
  • Tidskriftsartikel (refereegranskat)abstract
    • The determination of actinides at low levels using ICP-MS can be interfered by polyatomic ions appearing at the same nominal mass-to-charge ratio. In this work, interferences initially found when analysing plutonium in soil and sediment samples were identified as lanthanide phosphates and the formation of these species examined. It was found that high sample gas flow rates and low rf powers enhanced the formation of lanthanide phosphates. All lanthanides studied (La, Ce, Pr and Nd) formed phosphates, albeit to various extents and of slightly different compositions. Furthermore, the lanthanide phosphate formation was verified by introducing the source of phosphorus, hydroxyethylidene diphosphonic acid (HEDPA), in an [1][8]O enriched water solution. This experiment also revealed that the HEDPA is essentially completely dissociated in the plasma and that the interfering species are most likely formed during ion extraction.
  •  
41.
  • Nygren, Ulrika, et al. (författare)
  • Separation of plutonium from soil and sediment prior to determination by inductively coupled plasma mass spectrometry
  • 2003
  • Ingår i: Journal of Analytical Atomic Spectrometry. - 0267-9477 .- 1364-5544. ; 18:12, s. 1426-1434
  • Tidskriftsartikel (refereegranskat)abstract
    • The purpose of this work was to develop an optimised sample-preparation procedure for the determination of Pu in soil/sediment with ICP-MS. To start with, several different procedures were screened for their ability to separate plutonium and remove uranium. After the screening, two methods were applied on one soil (IAEA Soil6) and two sediment reference materials (IAEA300 and IAEA135). These methods were based on separation of Pu using TEVA and a combination of UTEVA and TRU resins, followed by elution of Pu with 0.1% hydroxylethylidene diphosphonic acid (HEDPA). A comparison was also made between sample preparation based on acid-leaching and complete digestion using lithium borate fusion. The highest yield of Pu (80%) was found with the procedure consisting of fusion followed by TEVA, while the decontamination from U showed large variations (RSD varying from 16–52%) with all procedures. No difference in the recovery of Pu was found between the two sample preparation techniques. The results of the quantitative determination in low resolution of 239Pu and 240Pu from the UTEVA + TRU-separation were significantly higher than those obtained by the TEVA procedure. An analysis in higher mass resolution displayed interfering peaks in the mass-region of Pu, and lanthanide-containing polyatomic ions were found to be a likely cause for these interferences. The procedure based on lithium borate fusion and separation using the TEVA-resin avoided such interferences and was therefore tested for repeatability over time on IAEA300. The stability of the method was good (RSD = 2.49% (n = 8)), with the exception of one value being significantly higher than the others. This result was confirmed by analysis in higher mass-resolution, which indicates an inhomogeneous distribution of Pu in the reference material, despite a sample intake of about 1 g.
  •  
42.
  • Nygren, Yvonne, 1965-, et al. (författare)
  • Hydrophilic interaction liquid chromatography (HILIC) coupled to inductively coupled plasma mass spectrometry (ICPMS) utilizing a mobile phase with a low-volatile organic modifier for the determination of cisplatin, and its monohydrolyzed metabolite
  • 2008
  • Ingår i: Journal of Analytical Atomic Spectrometry. - : Royal Society of Chemistry. - 0267-9477 .- 1364-5544. ; 23:7, s. 948-954
  • Tidskriftsartikel (refereegranskat)abstract
    • This study demonstrates the on-line coupling of hydrophilic interaction liquid chromatography (HILIC) to inductively coupled plasma mass spectrometry (ICPMS). A low volatile organic solvent, dimethylformamide (DMF), was used as organic modifier of the mobile phase to minimize the solvent loading of the ICP and thereby improve analyte sensitivity and method robustness. The concept was illustrated by the selective determination of cisplatin (cis-DDP), and its mono-hydrolyzed metabolite (MH-DDP). Species were separated on a 2.1 × 150 mm ZIC-HILIC column and detected on-line by selective platinum (m/z 194 and 195) monitoring, giving a detection limit of 2 pg Pt (0.2 ng ml-1). Compared to the use of the conventional solvent acetonitrile (AcN), with DMF, cis-DDP sensitivity was enhanced as much as 36 times and no addition of oxygen to the plasma was needed to avoid carbon depositions on instrumental parts. Furthermore, several non-identified platinum containing compounds were observed when using AcN as a result of unwanted reactions between this solvent and the analytes. No such species were observed when DMF was used. The molecular structures of eluting compounds were verified by electrospray ionization mass spectrometry. Combined with a simple sample treatment protocol, the HILIC-ICPMS system allowed determination of free intracellular cis-DDP in in-vitro grown T289 human malignant melanoma cells up to 60 min after exposure to 50 g ml-1 cis-DDP for 1 h. This work shows that HILIC-ICPMS is a potent hyphenated technique for the analysis of hydrophilic metal compounds and that the use of chromatographic mobile phases with low-volatile organic solvents may be a generic approach to improve analyte sensitivity and system robustness of HPLC-ICPMS when mobile phases with high amount of organic solvent are used.
  •  
43.
  • Olofsson, Rickard S., et al. (författare)
  • Performance characteristics of a tandem spray chamber arrangement in double focusing sector field ICP-MS
  • 2000
  • Ingår i: Journal of Analytical Atomic Spectrometry. - : Royal Society of Chemistry (RSC). - 0267-9477 .- 1364-5544. ; 15:6, s. 727-729
  • Tidskriftsartikel (refereegranskat)abstract
    • A tandem cyclone-Scott type spray chamber configuration combined with infrared heating and a low-flow Micromist nebulizer was evaluated for the use in a ICP-SFMS sample introduction system. The system provides about a 3-fold sensitivity gain and lower oxide formation compared to the standard introduction system, although matrix-induced signal suppression is more pronounced, especially for elements with high ionization potential. The technique was evaluated by accurate analysis of riverine water reference material SLRS-3 with generally good agreement with certified and literature values. Long-term precision at a 20rµgrlm1 concentration level was 0.7% RSD in low resolution and 1.6% RSD in medium resolution. Precision in the range 0.03-0.09% RSD for lead isotope ratios at 1rµgrlm1 was obtained.
  •  
44.
  • Pallavicini, Nicola, et al. (författare)
  • A high-throughput method for the determination of Os concentrations and isotope ratio measurements in small-size biological samples
  • 2013
  • Ingår i: Journal of Analytical Atomic Spectrometry. - : Royal Society of Chemistry (RSC). - 0267-9477 .- 1364-5544. ; 28:10, s. 1591-1599
  • Tidskriftsartikel (refereegranskat)abstract
    • An analytical method allowing multi-element characterization by external calibration, osmium (Os) concentration determination by isotope dilution (ID) and 187Os/188Os isotope abundance ratio measurement from a single sample preparation was developed. The method consists of microwave-assisted, closed-vessel acid digestion of small (0.01-0.4 g dry weight) biological samples spiked with Os solution enriched in a 190Os isotope followed by concentration and Os isotope ratio measurements using double-focusing, sector field inductively coupled plasma mass-spectrometry (ICP-SFMS) operated with methane addition to the plasma and solution nebulization (SN) sample introduction. For samples with Os content below 500 pg, complementary analysis using gas-phase introduction (GPI) on the remaining sample digests was performed. The use of disposable plastic lab ware for sample digestion and analysis by SN ICP-SFMS circumvents Os carry-over effects and improves the sample throughput and cost-efficiency of the method. For a 0.1 g dried sample, Os method limits of detection (MLODs) of 2 pg g -1 and 0.2 pg g-1 were obtained using SN or GPI, respectively. Long-term reproducibility of 187Os/188Os isotope abundance ratio measurements using the GPI approach was better than 1.5% RSD for our in-house control sample (moose kidney) with an Os concentration of approximately 5 pg g-1. Os data for several commercially available reference materials of biological or plant origin (not certified for Os) are presented. The method was used in the large scale bio-monitoring of free-living bank voles from an area affected by anthropogenic Os emissions.
  •  
45.
  • Pallavicini, Nicola, et al. (författare)
  • Cadmium isotope ratio measurements in environmental matrices by MC-ICP-MS
  • 2014
  • Ingår i: Journal of Analytical Atomic Spectrometry. - : Royal Society of Chemistry (RSC). - 0267-9477 .- 1364-5544. ; 29:9, s. 1570-1584
  • Tidskriftsartikel (refereegranskat)abstract
    • Various stages of an analytical method for high-precision cadmium (Cd) isotope ratio measurements by MC-ICP-MS (sample preparation, matrix separation, instrumental analysis and data evaluation) were critically evaluated and optimized for the processing of carbon-rich environmental samples. Overall reproducibility of the method was assessed by replicate preparation and Cd isotope ratio measurements in various environmental matrices (soil, sediment, Fe-Mn nodules, sludge, kidney, liver, leaves) and was found to be better than 0.1‰ (2σ for δ114Cd/110Cd) for the majority of samples. Cd isotope ratio data for several commercially-available reference materials are presented and compared with previously published results where available. The method was used in a pilot study focusing on the assessment of factors affecting Cd isotope composition in tree leaves. A summary of results obtained for a large number (n > 80) of birch (Betula pubescenes) leaves collected from different locations in Sweden and through the entire growing season is presented and potential reasons for observed variability in Cd isotope composition are discussed. Seasonal dynamics of element concentrations and isotope compositions in leaves were also compared for Os, Pb, Zn and Cd.
  •  
46.
  • Pontér, Simon, et al. (författare)
  • Chromium isotope ratio measurements in environmental matrices by MC-ICP-MS
  • 2016
  • Ingår i: Journal of Analytical Atomic Spectrometry. - 0267-9477 .- 1364-5544. ; 31:7, s. 1464-1471
  • Tidskriftsartikel (refereegranskat)abstract
    • An analytical procedure consisting of high pressure/temperature acid digestion using an UltraCLAVE system and a one pass, single column matrix separation using DOWEX AG 1X8 anion exchange resin was applied to the determination of Cr concentrations and δ53Cr in chromites, soils, and biological matrices (epiphytic lichens and mosses) using a combination of ICP-SFMS and MC-ICP-MS. The overall reproducibility of the method was assessed by replicate preparation and Cr isotope ratio measurements performed by different operators in multiple analytical sessions over a few months and was found to be 0.11‰ (2σ). The accuracy was evaluated using commercially available reference materials for which measured data were compared with certified values (for Cr concentrations) and previously published results (for isotope data). The results demonstrate a uniform Cr isotope composition in soil depth profiles sampled in different urban environments. A strong negative correlation between δ53Cr and Cr concentrations in lichens and mosses indicates that airborne Cr from local anthropogenic source(s) is depleted in heavy isotopes.
  •  
47.
  • Pontér, Simon, et al. (författare)
  • Chromium isotope ratio measurements in environmental matrices by MC-ICP-MS
  • 2016
  • Ingår i: Journal of Analytical Atomic Spectrometry. - : Royal Society of Chemistry (RSC). - 0267-9477 .- 1364-5544. ; 31:7, s. 1464-1471
  • Tidskriftsartikel (refereegranskat)abstract
    • An analytical procedure consisting of high pressure/temperature acid digestion using an UltraCLAVE system and a one pass, single column matrix separation using DOWEX AG 1X8 anion exchange resin was applied to the determination of Cr concentrations and delta Cr-53 in chromites, soils, and biological matrices (epiphytic lichens and mosses) using a combination of ICP-SFMS and MC-ICP-MS. The overall reproducibility of the method was assessed by replicate preparation and Cr isotope ratio measurements performed by different operators in multiple analytical sessions over a few months and was found to be 0.11 parts per thousand (2 sigma). The accuracy was evaluated using commercially available reference materials for which measured data were compared with certified values (for Cr concentrations) and previously published results (for isotope data). The results demonstrate a uniform Cr isotope composition in soil depth profiles sampled in different urban environments. A strong negative correlation between delta Cr-53 and Cr concentrations in lichens and mosses indicates that airborne Cr from local anthropogenic source(s) is depleted in heavy isotopes.
  •  
48.
  • Quétel, C. R., et al. (författare)
  • Methylmercury in tuna: demonstrating measurement capabilities and evaluating comparability of results worldwide from the CCQM P-39 comparison
  • 2005
  • Ingår i: Journal of Analytical Atomic Spectrometry. - : Royal Society of Chemistry (RSC). - 0267-9477 .- 1364-5544. ; 20, s. 1058-66
  • Tidskriftsartikel (refereegranskat)abstract
    • Six metrology institutes (NMIs) representing at the Comité International des Poids et Mesures (CIPM) 4 Member States of the Metre Convention and 2 international organisations, and 8 expert laboratories selected outside CIPM have compared their capabilities to quantitatively measure methylmercury (MeHg) in a prepared tuna material containing approximately 4.3 mg kg–1 Hg. This comparison was the object of the CIPM–Comité Consultatif pour la Quantité de Matière (CCQM) Pilot Study 39, organised by the Institute for Reference Materials and Measurements (IRMM), from the European Commission—Joint Research Centre. Beside the test material itself, a bottle of the BCR-464 tuna Certified Reference Material (CRM) and an ampoule of IRMM-670, a 202Hg isotope enriched MeHg candidate isotopic CRM, were distributed to all participants, who were free to apply the measurement strategy of their choice. Four, including 1 NMI, relied on external calibration or the method of standard additions, whereas the other 10 implemented an isotope dilution mass spectrometry (IDMS) approach and chose to use the IRMM-670 for their measurements. Alkaline digestion at room temperature (with manual shaking) or high temperature (under sonication, oven or hot plate conditions) was employed by most participants, with hydrochloric acid leaching the second most popular choice. Alkylation (4 phenylations, 4 ethylations and 3 propylations) in the aqueous phase was preferred by a large majority over butylation by the Grignard reaction. All participants were requested to estimate the uncertainty associated with their results and 9 out of 14 stated relative combined uncertainties below 6%(k= 2). Despite this apparent consensus, the perception of which factor caused the largest contribution to this estimation differed among participants because of the differences in the analytical methodologies deployed but also because of wide differences of the concepts of uncertainty estimation. The mixture mode(MM) median, calculated also from the measurement uncertainties stated by the participants, was 1.967 ± 0.204 × 10–5 mol kg–1(95% confidence). Twelve of the results were re-grouped within a range of less than 0.3 × 10–5 mol kg–1(MM median = 1.967 ± 0.162 × 10–5 mol kg–1, 95% confidence): they nearly all (1 exception) overlapped with each other within k= 2 stated uncertainties. For the other 2 results the uncertainty seemed to have been particularly underestimated as they lay, respectively, at more than 20% above and less than –40% below the overall average. The relative standard deviation of the results of 9 laboratories out of the 10 that applied IDMS was about 2.6%. It can be assumed from the degree of equivalence shown by 12 out of 14 study participants that, at present, laboratories worldwide are potentially able to supply accurate results for MeHg in fish-type matrices (containing about 2 × 10–5 mol kg–1) within ±10% uncertainty. This encouraging outcome permitted scheduling of a follow-up CCQM-K43 key comparison for a lower MeHg content level in salmon tissues.
  •  
49.
  • Qvarnström, Johanna, et al. (författare)
  • Mercury species transformations during sample pre-treatment of biological tissues studied by HPLC-ICP-MS
  • 2002
  • Ingår i: Journal of Analytical Atomic Spectrometry. - : RSC Publishing. - 0267-9477 .- 1364-5544. ; 17:11, s. 1486-1491
  • Tidskriftsartikel (refereegranskat)abstract
    • A high-performance liquid chromatography (HPLC) system with a C18 column and an aqueous phase eluent (0.08% ammonium acetate and 0.02% L-cysteine) was directly connected to an inductively coupled plasma mass spectrometer (ICP-MS). HPLC-ICP-MS was used to study the abiotic formation of methylmercury, CH3Hg+, from inorganic mercury, Hg2+, as well as demethylation of CH3Hg+ to Hg2+ in biological tissues during treatment with tetramethylammonium hydroxide (TMAH) followed by pH adjustment with citric or acetic acid. Enriched isotope standards from CH3198Hg+ and 201Hg2+ were added to the samples to monitor species transformation and to apply species-specific isotope dilution (SSID) calibration. Depending on the type of sample matrix, up to 11.5% of added Hg2+ was methylated and up to 6.26% CH3Hg+ was demethylated to Hg2+. Methylation of Hg2+ probably takes place mainly during and after pH adjustment and it decreases after prolonged TMAH treatment. To minimize abiotic methylation, it is therefore recommended to proceed with pH adjustment after samples have been treated with TMAH for 24 h. There is no significant difference in the degree of methylation using citric or acetic acid.
  •  
50.
  • Ranebo, Ylva, et al. (författare)
  • Improved isotopic SIMS measurements of uranium particles for nuclear safeguard purposes
  • 2009
  • Ingår i: Journal of Analytical Atomic Spectrometry. - : Royal Society of Chemistry (RSC). - 1364-5544 .- 0267-9477. ; 24:3, s. 277-287
  • Tidskriftsartikel (refereegranskat)abstract
    • The isotopic analysis of particles containing sub-pg to pg levels of uranium, released from nuclear material handling, has been proven as an efficient tool for international safeguard purposes. Precise and accurate measurement of both enrichment and the minor isotopes is, however, a challenging analytical task due to the low levels of material. One of the mainstay techniques for particle measurement is Secondary Ion Mass Spectrometry (SIMS), this study evaluates the analytical benefit of an alternative in the form of large geometry SIMS (LG-SIMS), which combines high transmission with high mass resolution. We report here that LG-SIMS instruments provide a significantly better measurement quality than the small geometry SIMS as almost all isobaric background interferences are removed at a high useful ion yield. Useful yield measurements, performed on uranium oxide particles with calibrated uranium content, showed an overall useful yield of 1.2% for the LG-SIMS at a mass resolution of 3000. These improvements were then demonstrated by comparing results from actual nuclear inspection samples measured on both instruments. Additional benefits include an increased ability to detect particles of interest in a dust matrix while simultaneously reducing the time of sample analysis. An evaluation on the performance of LG-SIMS compared to Thermal Ion Mass Spectrometry (TIMS) is also presented. This evaluation shows that LG-SIMS has an advantage due to its high ion yield but with a limitation in the detection limit of U-236 at higher enrichments due to the necessity for a hydrogen correction.
  •  
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