| 1. |
- Qvarnström, Johanna, et al.
(författare)
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Determination of methylmercury, ethylmercury, and inorganic mercury in mouse tissues, following administration of thimerosal, by species-specific isotope dilution GC-inductively coupled plasma-MS
- 2003
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Ingår i: Analytical Chemistry. - : American Chemical Society (ACS). - 0003-2700 .- 1520-6882. ; 75:16, s. 4120-4124
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Tidskriftsartikel (refereegranskat)abstract
- Isotopically enriched HgO standards were used to synthesize CH 3200Hg+ and C2H5199Hg+ using Grignard re-agents. These species were employed for isotope dilution GC-ICPMS to study uptake and biotransformation of ethylmercury in mice treated with thimerosal, (sodium ethylmercurithiosalicylate) 10 mg L-1 in drinking water ad libitum for 1, 2.5, 6, or 14 days. Prior to analysis, samples were spiked with aqueous solutions of CH3200Hg+, C2H 5199Hg+, and 201Hg2+ and then digested in 20% tetramethylammonium hydroxide and extracted at pH 9 with DDTC/toluene. Extracted mercury species were reacted with butylmagnesium chloride to form butylated derivatives. Absolute detection limits for CH 3Hg+, C2H5Hg+, and Hg2+ were 0.4, 0.2, and 0.6 pg on the basis of 3s of five separate blanks. Up to 9% of the C2H5Hg+ was decomposed to Hg2+ during sample preparation, and it is therefore crucial to use a species-specific internal standard when determining ethylmercury. No demethylation, methylation, or ethylation during sample preparation was detected. The ethylmercury component of thimerosal was rapidly taken up in the organs of the mice (kidney, liver, and mesenterial lymph nodes), and concentrations of C2H5Hg+ as well as Hg2+ increased over the 14 days of thimerosal treatment. This shows that C2H5Hg+ in mice to a large degree is degraded to Hg2+. Increased concentrations of CH3Hg + were also observed, which was found to be due to impurities in the thimerosal.
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| 2. |
- Björn, Erik, et al.
(författare)
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Calibration errors due to variations in peak characteristics in the measurement of transient signals by inductively coupled plasma-scanning mass spectrometry
- 2002
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Ingår i: Journal of Analytical Atomic Spectrometry. - : Royal Society of Chemistry (RSC). ; 17, s. 1582-8
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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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| 3. |
- Björn, Erik, et al.
(författare)
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Introduction of high carbon content solvents into inductively coupled plasma mass spectrometry by a direct injection high efficiency nebuliser
- 2003
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Ingår i: Analytical and Bioanalytical Chemistry. - : Springer Science and Business Media LLC. - 1618-2642. ; 376:2, s. 274-8
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Tidskriftsartikel (refereegranskat)abstract
- A preliminary investigation on the introduction of high carbon content solvents into inductively coupled plasma mass spectrometry (ICP-MS) by a direct injection high efficiency nebuliser (DIHEN) is presented. Ethanol, hexane, toluene and a natural gas condensate were introduced using a flow injection system. The performance for determinations of total concentrations of mercury present in organic solvents as different species was evaluated. The most critical operating parameters were the nebuliser gas flow rate and amount of oxygen added to the plasma. For the DIHEN a nebuliser gas flow rate of 0.3 L minm1 and 50 mL minm1 of oxygen added to the plasma auxiliary gas flow gave stable conditions and high analyte sensitivity. Species recoveries for HgCl2, CH3HgCl, (CH3)2Hg and Hg0 in hexane were 99-4, 101-4, 95-4 and 104-7%, respectively. Detection limit for mercury in hexane was 85 pg mLm1 based on 3† of a 201Hg-spiked blank. A gradual deposition was observed at the nebuliser tip, partly blocking the gas annulus. The rate of deposition seemed to be related to the amount of carbon introduced through the nebuliser. With the optimised conditions used in this work, the nebuliser could be used for approximately 50 hexane samples before cleaning was necessary.
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| 4. |
- Björn, Erik, et al.
(författare)
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Non-spectral interference effects in inductively coupled plasma mass spectrometry using direct injection high efficiency and microconcentric nebulisation
- 2001
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Ingår i: JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY. - : Royal Society of Chemistry (RSC). ; 16, s. 4-11
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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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| 5. |
- Elsayed, Moneim, et al.
(författare)
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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
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Ingår i: JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY. - : Royal Society of Chemistry (RSC). ; 15:6, s. 697-703
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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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| 6. |
- Frech, Wolfgang, et al.
(författare)
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Characterization of a pressurizable two-step atomizer for atomic absorption spectrometry
- 2000
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Ingår i: Spectrochimica Acta Part B: Atomic Spectroscopy. ; 55:5, s. 461-72
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Tidskriftsartikel (refereegranskat)abstract
- A two-step atomizer consisting of a transversely heated atomization tube with integrated contacts and a cup furnace for sample vaporization was constructed. The system could accommodate tubes of various lengths and it could be operated at selected pressures. There was no physical contact between the tube and the cup and mainly diffusion was responsible for the sample vapour transport from the cup to the tube. Under these conditions there was an unavoidable loss by 40% of the peak area signals due to the gap between the cup and the tube. For a 24-mm tube, characteristic masses were on the average three times lower than for the state of the art transverse heated graphite atomizers (THGA). By de-coupling the processes of analyte vaporization and atomization the dynamic working range could be increased by three to six times using conventional measurements by atomic absorption spectrometry (AAS). In this case the cup temperature and hence the rate of analyte transport from the cup to the tube was controlled such that atom density in the tube did not exceed the linear range of the absorbance measurement. Carrying out clean-out steps at reduced pressure decreased memory effects.
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| 7. |
- Hermann, G, et al.
(författare)
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Platform-to-platform sample transfer, distribution, dilution, and dosing via electrothermal vaporization and electrostatic deposition
- 2004
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Ingår i: Spectrochimica Acta Part B: Atomic Spectroscopy. - : Elsevier BV. - 0584-8547. ; 59:5, s. 737-48
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Tidskriftsartikel (refereegranskat)abstract
- A novel system for solid sample pretreatment, handling and dosing for analytical atomic spectrometry is described. A primary solid or liquid sample is vaporized in a graphite furnace and then condensed in a specially designed condensation zone. On the further transport path, the analyte aerosol can be diluted and distributed in pre-set ratios in the laboratory made flow control system. Applying a corona discharge, aerosol particulates are then quantitatively re-collected by means of intra-furnace electrostatic precipitation on the platform of another graphite furnace or by external precipitation on one or a set of platforms. This makes possible to produce a set of secondary platforms with equal analyte compositions from one individual primary sample. Such multitudes allow sequential multi-element determinations with single-element instrumentation or comparative measurements with different techniques. Furthermore, the described procedure allows external thermal sample pretreatment with preceding pyrolysis and additional vaporization, condensation, and re-precipitation that significantly reduces or removes the sample matrix. Owing to different losses, transport efficiencies of electrothermal vaporization (ETV) instrumentation depend on analyte element, matrix, vaporization temperature, ramp rate, and tube history. In order to reduce the losses and therewith such dependencies of the losses, new laboratory constructed ETV unit with analyte condensation in an axially focusing upstream convection zone has been constructed. Analytical performance of the new setup is compared with the performance of a commercial end-on flow-through ETV unit when analyzing both liquid dosed samples and certified solid reference materials. The new system shows much higher transport efficiencies that are, in addition, more uniform for elements of different volatility. The effects of chemical sample modifiers and elements supporting analyte condensation are studied. Most of the analytical measurements were carried out with a continuum source coherent forward scattering multi-element spectrometer. Comparative measurements were also carried out independently in the co-authors’ laboratories with atomic absorption and inductively coupled plasma mass spectrometry techniques.
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| 8. |
- Iregren, A, et al.
(författare)
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Effects on the nervous system in different groups of workers exposed to aluminium
- 2001
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Ingår i: Occupational and Environmental Medicine. ; 58, s. 453-60
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE - To investigate possible neurotoxic effects in groups of aluminium pot room and foundry workers, aluminium welders, and a small group of workers exposed to aluminium in the production of flake powder.METHODS - Exposure to aluminium was evaluated with aluminium concentrations in blood and urine as well as a questionnaire. The groups exposed to aluminium were compared with a group of mild steel welders. Neurotoxic effects were studied with mood and symptom questionnaires and several psychological and neurophysiological tests.RESULTS - The pot room and foundry workers showed very low aluminium uptake as their aluminium concentrations in blood and urine were close to normal, and no effects on the nervous system were detected. The group of workers exposed to flake powder had high concentrations of aluminium in blood and urine, even higher than those of the aluminium welders. However, aluminium could not be shown to affect the functioning of the nervous system in flake powder producers. Although significant effects could not be shown in the present analysis of the data on welders, the performance of the welders exposed to high concentrations of aluminium was affected according to the analyses in the original paper from this group.CONCLUSIONS - For the pot room and foundry workers no effects related to the exposure to aluminium could be found. For the group of flake powder producers exposed for a short term no effects on the nervous systems were evident despite high levels of exposure. Due to the high concentrations of aluminium in the biological samples of this group, measures to reduce the exposure to aluminium are recommended, as effects on the central nervous system might develop after protracted exposures. However, this assumption needs to be verified in further studies.
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| 9. |
- Kumar, Sunil J., et al.
(författare)
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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
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Ingår i: Journal of Analytical Atomic Spectrometry. - London : Royal Society of Chemistry. - 0267-9477 .- 1364-5544. ; 19:3, s. 368-372
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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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| 10. |
- Kumar, Sunil Jai, et al.
(författare)
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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
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Ingår i: Journal of Analytical Atomic Spectrometry. - : Royal Society of Chemistry (RSC). - 0267-9477 .- 1364-5544. ; 18:714-9
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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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