| 1. |
- Aminlashgari, Nina, et al.
(författare)
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Nanocomposites as novel surfaces for laser desorption ionization mass spectrometry
- 2011
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Ingår i: Analytical Methods. - : Royal Society of Chemistry (RSC). - 1759-9660 .- 1759-9679. ; 3:1, s. 192-197
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Tidskriftsartikel (refereegranskat)abstract
- The possibility to utilize nanocomposite films as easy-to-handle surfaces for surface assisted laser desorption ionization-mass spectrometry (SALDI-MS) of small molecules, such as pharmaceutical compounds, was evaluated. The signal-to-noise values of acebutolol, propranolol and carbamazepine obtained on the nanocomposite surfaces were higher than the values obtained on plain PLA surface showing that the nanoparticles participate in the ionization/desorption process even when they are immobilized in the polymer matrix. The advantages of nanocomposite films compared to the free nanoparticles used in earlier studies are the ease of handling and reduction of instrument contamination since the particles are immobilized into the polymer matrix. Eight inorganic nanoparticles, titanium dioxide, silicon dioxide, magnesium oxide, hydroxyapatite, montmorillonite nanoclay, halloysite nanoclay, silicon nitride and graphitized carbon black at different concentrations were solution casted to films with polylactide (PLA). There were large differences in signal intensities depending on the type of drug, type of nanoparticle and the concentration of nanoparticles. Polylactide with 10% titanium oxide or 10% silicon nitride functioned best as SALDI-MS surfaces. The limit of detection (LOD) for the study was ranging from 1.7 ppm up to 56.3 ppm and the signal to noise relative standard deviations for the surface containing 10% silicon nitride was approximately 20-30%. Scanning electron microscopy demonstrated in most cases a good distribution of the nanoparticles in the polymer matrix and contact angle measurements showed increasing hydrophobicity when the nanoparticle concentration was increased, which could influence the desorption and ionization. Overall, the results show that nanocomposite films have potential as surfaces for SALDI-MS analysis of small molecules.
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| 2. |
- Antonio Lopez-Lopez, Jose, et al.
(författare)
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Simple hollow fiber liquid membrane based pre-concentration of silver for atomic absorption spectrometry
- 2014
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Ingår i: Analytical Methods. - : Royal Society of Chemistry (RSC). - 1759-9660. ; 6:5, s. 1462-1467
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Tidskriftsartikel (refereegranskat)abstract
- Silver pollution has gained attention in the last few years because silver is being massively used as a bactericide in self-care, medical and textile products. Difficulties of Ag determination are associated with the very low concentrations in which it is normally found (ng L-1) and the nature of the sample matrix. Standard methods such as liquid-liquid extraction (LLE) are regularly used. Alternatively, liquid phase micro-extraction (LPME) appears to be an environmentally friendly tool for sample treatment that offers higher pre-concentration factors. This allows the determination of ultra-trace levels of silver using standard instrumental techniques such as atomic absorption spectrometry. In this work, a hollow fiber LPME is proposed. Silver pre-concentration has been conducted using tri-isobutylphosphine sulphide (TIBPS) as a carrier from the sample to an acceptor solution through a solvent placed in the fiber pores. Accurel-PP 50/280 fibers with an internal volume of 20 mu L were used for 50 mL samples. After optimization, 0.1 M KNO3 in the sample, 0.1 M TIBPS in dihexyl ether as the organic phase and 1 M Na2S2O3 in the acceptor solution were established. The system offers enrichment factors of 1053 times, a limit of detection of 1.16 ng L-1. This method improves the limit of detection of the most recent liquid micro-extraction methods for silver pre-concentration coupled with GFAAS, being in this case comparable to ICP-MS detection based techniques.
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| 3. |
- Bergman, Nina, et al.
(författare)
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Quantitative determination of the Ru(bpy)(3)(2+) cation in photochemical reactions by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry
- 2014
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Ingår i: Analytical Methods. - : Royal Society of Chemistry (RSC). - 1759-9660 .- 1759-9679. ; 6:21, s. 8513-8518
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Tidskriftsartikel (refereegranskat)abstract
- The coordination compound of Ru(II) with three 2,2'-bipyridine ligands possesses a potent photosensitization capacity for electron- and energy-transfer processes. In combination with salts of peroxydisulfate acid as sacrificial electron acceptors, Ru(bpy)(3)(2+) is widely used for photocatalytic oxidative transformations in organic synthesis and water splitting. The drawback of this system is that bipyridine degrades under the resulting strongly oxidative conditions, the concentration of Ru(bpy)(3)(2+) diminishes, and the photocatalytic reaction eventually stops. A commonly employed assay for the determination of Ru(bpy)(3)(2+), UV-Vis spectroscopy, has low selectivity and does not distinguish between the intact complex and its decayed forms. Here, we report a matrix assisted laser desorption/ionisation mass spectrometric method for the quantitative analysis of Ru(bpy)(3)(2+) in photochemical reaction mixtures. The developed method was successfully used for the determination of intact Ru(bpy)(3)(2+) during the course of the water photooxidation reaction. The significant difference between the results of MALDI MS and UV-Vis analyses was observed.
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| 4. |
- Boström, Marja L., et al.
(författare)
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A specific, highly enriching and "green" method for hollow fiber liquid phase microextraction of ionizable pharmaceuticals from fish tissue
- 2014
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Ingår i: Analytical Methods. - : Royal Society of Chemistry (RSC). - 1759-9660. ; 6:15, s. 6031-6037
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Tidskriftsartikel (refereegranskat)abstract
- Ionizable pharmaceuticals are a class of emerging contaminants that pose a challenge to analytical chemistry due to their low environmental concentrations. To measure such low concentrations in organism tissue, e.g. fish muscle, specific extraction techniques minimizing co-extraction and interference alongside providing high enrichment of the compounds are needed. In this study we present a technique using hollow fiber liquid phase microextraction which is selective and highly enriching due to a pH gradient across a selective membrane, trapping ions in the extract. Microextraction minimizes the use of organic solvents, thereby making the technique "green". We used high volume pharmaceuticals for method development, specifically, the weak acids ketoprofen, naproxen, diclofenac and ibuprofen, and the weak bases fluoxetine and sertraline. Lyophilized tissue extraction gave higher enrichment than fresh tissue extraction and concentration enrichment factors ranged from 1900 to 3000 times. Method detection limits with the analysis instruments used in this study were for ketoprofen, 0.23 ng g(-1) fish tissue; naproxen, 0.32 ng g(-1) fish tissue; diclofenac, 0.12 ng g(-1) fish tissue; ibuprofen, 0.34 ng g-1 fish tissue; fluoxetine, 13 ng g-1. fish tissue and sertraline, 23 ng g(-1) fish tissue. All analytes were successfully detected in tissue from fish exposed live via spiked water. The resulting extraction parameters shown in this study suggest the developed technique to be a useful work up method for extensive environmental data collection as well as for toxicokinetic studies.
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| 5. |
- Decker, Daniel, et al.
(författare)
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A luminescence-based assay of UDP-sugar producing pyrophosphorylases
- 2014
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Ingår i: Analytical Methods. - 1759-9660 .- 1759-9679. ; 6:1, s. 57-61
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Tidskriftsartikel (refereegranskat)abstract
- A coupled luminescence assay was applied to monitor pyrophosphate (PPi) production by either purified barley UDP-glucose pyrophosphorylase (UGPase) or purified Leishmania UDP-sugar pyrophosphorylase (USPase). In the assay, the PPi produced by the pyrophosphorylases was converted to ATP by ATP-sulfurylase, and the ATP produced was linked to luminescent light formation through the action of firefly luciferase. The assay allowed for a quantitative measurement of UGPase and USPase activities, down to a pmol per min level. The activities were linear with time and proportional to the amount of the enzyme added, and were neither affected by Pi nor by DTT. For UGPase, K-m values with UTP and Glc-1-P were 0.14 and 0.26 mM, respectively, whereas for USPase the respective K-m values with UTP, Glc-1-P and Gal-1-P were 0.4, 2.9 and 3.9 mM. Possible applications of the luminescence-based assay for not only UDP-sugar producing pyrophosphorylases, but also other types of pyrophosphorylases are discussed.
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| 6. |
- Do, Lan, et al.
(författare)
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Modular pressurized liquid extraction for simultaneous extraction, clean-up and fractionation of PCDD/Fs in soil, sediment and sludge samples
- 2013
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Ingår i: Analytical Methods. - : RSC Publishing. - 1759-9660 .- 1759-9679. ; :5, s. 1231-1237
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Tidskriftsartikel (refereegranskat)abstract
- Modular pressurized liquid extraction (M-PLE) procedures were developed for simultaneous extraction, clean-up and fractionation of polychlorinated dioxins and furans (PCDD/Fs) in soil, sediment and sludge samples. The procedures utilize two coupled extraction cells: an upstream cell filled with the sample and layers of silica and acid- and base-modified silica, and a downstream cell filled with activated carbon. The silica layers were added to remove polar or hydrolysable matrix components, and the carbon to perform planarity-based fractionation. Two solvent systems (dichloromethane–heptane, DCM–Hp and diethyl ether–heptane, DEE–Hp) and two activated carbon loads (1% and 3% carbon on Celite) were evaluated using certified reference materials (CRM-529 and WMS-01) and materials from previous inter-calibration studies. Using any of the four procedures, data statistically equivalent to the certified or reference values were obtained. The M-PLE procedure using DCM–Hp and 1% carbon sometimes extracted the reference materials more efficiently than the reference methods, while the DEE–Hp procedure extracted them equally efficient, offering an alternative with less environmental impact. The methods with 1% carbon on Celite produced sufficiently pure extracts for sample loads up to one gram, but for greater sample loads the higher carbon load (3% carbon on Celite) was required to avoid breakthrough of target analytes. The new streamlined procedures are fast, cost-efficient, involve relatively low environmental impact (in the case of DEE–Hp) and are well suited for high-throughput analysis of solid samples, e.g. in connection with environmental monitoring campaigns and major soil remediation efforts.
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| 7. |
- Giesecke, Marianne, et al.
(författare)
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The protonation state and binding mode in a metal coordination complex from the charge measured in solution by electrophoretic NMR
- 2013
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Ingår i: Analytical Methods. - : Royal Society of Chemistry (RSC). - 1759-9660 .- 1759-9679. ; 5:7, s. 1648-1651
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Tidskriftsartikel (refereegranskat)abstract
- We measured with high accuracy the effective charge of a uranium (VI)-AMP complex by electrophoretic NMR (eNMR). Using the same method, the degree of counterion association is also assessed which leads to a quantitative determination of the nominal charge which then provides the degree of ligand deprotonation in the complex. This demonstrates a new application of eNMR for resolving structural details of supramolecular complexes.
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| 8. |
- Hedberg, Jonas, et al.
(författare)
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Ion selective electrodes are not suitable for measurements of silver ion concentrations in alkaline carbonate media
- 2013
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Ingår i: Analytical Methods. - : RSC Publishing. - 1759-9660 .- 1759-9679. ; 5:4, s. 1068-1070
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Tidskriftsartikel (refereegranskat)abstract
- An ion selective electrode (ISE) for determination of the labile silver ion concentration in carbonate containing solutions of pH 10 was seen to give incorrect results due to shifts in the Ag vertical bar Ag+ equilibrium. This drawback was not the case for the differential pulse anodic stripping voltammetry (DPASV) method.
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| 9. |
- Makaraviciute, Asta, et al.
(författare)
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Antibody fragment immobilization on planar gold and gold nanoparticle modified quartz crystal microbalance with dissipation sensor surfaces for immunosensor applications
- 2014
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Ingår i: Analytical Methods. - : Royal Society of Chemistry. - 1759-9660 .- 1759-9679. ; 6:7, s. 2134-2140
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Tidskriftsartikel (refereegranskat)abstract
- Immunosensors are bioaffinity sensors incorporating immune system molecules that are utilized for analyte recognition and signal transduction yielding a measurable signal upon analyte detection. A lot of effort has been made to optimize the immobilization matrix on the sensor surface since the outcome of the ligand immobilization procedure determines sensitivity, specificity and longevity of the developed immunosensor. In this work, antibodies against bovine leukemia virus antigen gp51 were chemically reduced to "half" antibody fragments that were later employed as recognition ligands. Antibody fragments at different concentrations were immobilized via thiolate bonds on planar gold and gold nanoparticle modified surfaces of a quartz crystal microbalance with dissipation sensor. Antibody fragment immobilization and interaction with antigen were investigated. Antibody fragment surface mass densities after the immobilization on planar gold and gold nanoparticle modified sensor surfaces were directly dependent on the initial antibody concentration. The highest analytical response was exhibited by antibody fragments immobilized at the smallest surface mass density on planar gold and gold nanoparticle modified surfaces. Bovine leukemia virus antigen gp51 interaction with antibody fragments was compared with non-specific gp51 interaction with bovine serum albumin on planar gold and gold nanoparticle modified surfaces by employing Delta D/Delta f plots.
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| 10. |
- Masala, Silvia, et al.
(författare)
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Pressurized liquid extraction as an alternative to the Soxhlet extraction procedure stated in the US EPA method TO-13A for the recovery of polycyclic aromatic hydrocarbons adsorbed on polyurethane foam plugs
- 2014
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Ingår i: Analytical Methods. - : Royal Society of Chemistry (RSC). - 1759-9660 .- 1759-9679. ; 6:20, s. 8420-8425
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Tidskriftsartikel (refereegranskat)abstract
- The aim of the present study was to develop a pressurized liquid extraction (PLE) method as an alternative to the relatively time consuming Soxhlet extraction procedure described in the United States Environmental Protection Agency (US EPA) method TO-13A for the extraction of PAHs adsorbed onto polyurethane foam plugs (PUFs). For this purpose PUF air samples were collected and split into two parts: one part extracted using PLE and the other one using Soxhlet extraction. Comparable PAH concentrations were obtained upon analysis of the extracts showing that the PLE method developed in this work is a more convenient choice than the commonly used Soxhlet extraction technique proposed by US EPA for the determination of PAHs in air samples. In fact, the developed PLE method required shorter assay times (minutes versus hours), less solvent consumption and simpler operational methods. The exhaustiveness of the developed PLE method was evaluated using repeat static extraction cycles, demonstrating an extraction efficiency for the PAHs of greater than 99%. The PLE method was then applied to diesel exhaust and wood smoke PUF samples showing an extraction efficiency for the PAHs of greater than 93% and 96%, respectively. Furthermore, a PLE method for PUF cleaning was developed as well and employed as an alternative to Soxhlet extraction. The PLE methods developed for cleaning and extracting PUFs presented in this work are suitable to be used in mutagenicity studies using the Ames Salmonella assay as no mutagenicity was found in the PLE generated blanks
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| 11. |
- Murphy, Kathleen, 1972, et al.
(författare)
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Fluorescence spectroscopy and multi-way techniques. PARAFAC
- 2013
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Ingår i: Analytical Methods. - : Royal Society of Chemistry (RSC). - 1759-9679 .- 1759-9660. ; 5:23, s. 6557-6566
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Tidskriftsartikel (refereegranskat)abstract
- PARAllel FACtor analysis (PARAFAC) is increasingly used to decompose fluorescence excitation emission matrices (EEMs) into their underlying chemical components. In the ideal case where fluorescence conforms to Beers Law, this process can lead to the mathematical identification and quantification of independently varying fluorophores. However, many practical and analytical hurdles stand between EEM datasets and their chemical interpretation. This article provides a tutorial in the practical application of PARAFAC to fluorescence datasets, demonstrated using a dissolved organic matter (DOM) fluorescence dataset. A new toolbox for MATLAB is presented to support improved visualisation and sensitivity analyses of PARAFAC models in fluorescence spectroscopy. © 2013 The Royal Society of Chemistry.
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| 12. |
- Murphy, Kathleen, 1972, et al.
(författare)
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OpenFluor- an online spectral library of auto-fluorescence by organic compounds in the environment
- 2014
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Ingår i: Analytical Methods. - : Royal Society of Chemistry (RSC). - 1759-9679 .- 1759-9660. ; 6:3, s. 658-661
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Tidskriftsartikel (refereegranskat)abstract
- An online repository of published organic fluorescence spectra has been developed, which can be searched for quantitative matches with any set of unknown spectra. It fills a critical gap by increasing access to measured and modelled (PARAFAC) spectra, and linking across studies and systems to reveal "global" fluorescence trends.
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| 13. |
- Nasef, Hany, et al.
(författare)
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Labelless electrochemical melting curve analysis for rapid mutation detection
- 2010
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Ingår i: Analytical Methods. - : Royal Society of Chemistry. - 1759-9660 .- 1759-9679. ; 2:10, s. 1461-1466
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Tidskriftsartikel (refereegranskat)abstract
- In the post-genome era there is an increasing demand for cost effective and rapid methods for thedetection of specific mutations and single nucleotide polymorphisms. Here we describe a method forthe rapid detection of mutations exploiting labelless electrochemical melting curve analysis, using thedetection of the cystic fibrosis associated DF508 mutant as a model. A 21-base long thiolated probe,complementary to the region of Exon 10 of the cystic fibrosis transmembrane regulatory gene where theDF508 mutation lies, was immobilised on a gold electrode and hybridised to a synthetic analogue ofsingle stranded PCR products for each of the mutant (85 bases) and wild type (82 bases) targets.Experimental conditions were optimised to exploit the guanine-specific interaction of the electroactiveindicator, methylene blue. Upon hybridisation of the immobilised probe to the target, the number ofguanine bases present in close proximity with the sensor surface increased from 3 to 14, resulting ina significant increase in signal. Ramping of the temperature caused denaturation of the on-surfaceimmobilised duplex and a concomitant reduction in signal. From the first derivative of the meltingcurves a clear differentiation between the mutant and wild-type target could be observed. The proposedapproach can be extended to array based melting curve analysis, allowing the simultaneous detection ofmultiple mutations and SNPs, and moreover the melting properties observed can also be used to designgenosensors for single target detection.
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| 14. |
- Onoshima, Daisuke, et al.
(författare)
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A deep microfluidic absorbance detection cell replicated from a thickly stacked SU-8 dry film resist mold
- 2012
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Ingår i: Analytical Methods. - : Royal Society of Chemistry (RSC). - 1759-9660 .- 1759-9679. ; 4, s. 4368-4372
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Tidskriftsartikel (refereegranskat)abstract
- Dry film resist SU-8 was used to make a thick mold for soft lithography of a poly(dimethylsiloxane) (PDMS) microfluidic chip with deep channels. The stacking of the SU-8 film enabled an ultra-thick (up to 500 μm) resist process on Si wafer. This process was fast and highly reproducible compared with the conventional liquid SU-8 process. The deep channel in the PDMS chip was utilized as a micro-flow cell for sensitive absorbance measurement. Sunset Yellow FCF dye was used to demonstrate absorption spectroscopy in the deep channel. Since the channel depth was proportional to the optical path length, which was proportional to the absorbance value, the PDMS chip achieved a detection limit (15.9 μM) comparable to U- or Z-shaped microfabricated absorbance detection cells in glass. Calibration curves for different solution concentrations were obtained with good R2 values (∼1). © 2012 The Royal Society of Chemistry.
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| 15. |
- Oppong Bekoe, Samuel, et al.
(författare)
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Determination of thirteen antibiotics in drug products : a new LC-MS/MS tool for screening drug product quality
- 2014
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Ingår i: Analytical Methods. - 1759-9660 .- 1759-9679. ; 6, s. 5847-5855
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Tidskriftsartikel (refereegranskat)abstract
- Poor quality antibiotic medicines in circulation in Sub-Saharan Africa continue to be a burden. Pharmaceutical trade in substandard and counterfeit medicines is on the rise. The chemical quality of antibiotics dispensed in health facilities and recognised drug outlets in Ghana, when compromised, could be a major drawback to efforts made in fighting antibiotic resistance globally. To improve on antibiotic drug quality monitoring, a liquid chromatography-tandem mass spectrometry (LC-MS/MS) methodology, which is capable of quantifying thirteen antibiotics in drug products, was developed and validated in present work. The methodology was applied to various drug products including tablets, capsules, suspensions, syrups, intravenous and injection solutions as well as ear and eye droplets used as essential medicines in a Sub-Saharan country, Ghana.
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| 16. |
- Oppong Bekoe, Samuel, et al.
(författare)
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Determination of thirteen antibiotics in drug products : a new LC-MS/MS tool for screening drug product quality
- 2014
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Ingår i: Analytical Methods. - : Royal Society of Chemistry. - 1759-9660 .- 1759-9679. ; 6, s. 5847-5855
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Tidskriftsartikel (refereegranskat)abstract
- Poor quality antibiotic medicines in circulation in Sub-Saharan Africa continue to be a burden. Pharmaceutical trade in substandard and counterfeit medicines is on the rise. The chemical quality of antibiotics dispensed in health facilities and recognised drug outlets in Ghana, when compromised, could be a major drawback to efforts made in fighting antibiotic resistance globally. To improve on antibiotic drug quality monitoring, a liquid chromatography-tandem mass spectrometry (LC-MS/MS) methodology, which is capable of quantifying thirteen antibiotics in drug products, was developed and validated in present work. The methodology was applied to various drug products including tablets, capsules, suspensions, syrups, intravenous and injection solutions as well as ear and eye droplets used as essential medicines in a Sub-Saharan country, Ghana.
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| 17. |
- Ripszam, Matyas, et al.
(författare)
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Elimination of interferences caused by simultaneous use of deuterated and carbon-13 standards in GC-MS analysis of polycyclic aromatic hydrocarbons (PAHs) in extracts from passive sampling devices
- 2013
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Ingår i: Analytical Methods. - : Royal Society of Chemistry (RSC). - 1759-9660 .- 1759-9679. ; 5:12, s. 2925-2928
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Tidskriftsartikel (refereegranskat)abstract
- Two types of isotope-labelled reference compounds are typically used for the passive sampling of polycyclic aromatic hydrocarbons. One type is added before the exposure of the sampler and is called a performance reference compound (PRC). The other is the laboratory internal standard, which is spiked into the sample after extraction (dialysis) from the membrane and is used for quantification. Generally, PRCs are deuterium-labelled while internal standards are C-13-labelled. Interference originating from the internal standards occurs when the molecular ions of the PRCs gradually lose deuterium in the ion source to generate fragments that overlap with the molecular ions of the C-13-labelled internal standards. This can cause significant systematic errors in quantification. Gas chromatography-high resolution time-of-flight mass spectrometry (GC-HRTOF-MS) was used to investigate the degree of interference at varying virtual resolutions of the MS instrument, and it was shown that many of the spectral interferences can be avoided by using high MS resolutions (35 000 or better).
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| 18. |
- Salomonsson, Matilda Lampinen, et al.
(författare)
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Development and in-house validation of a method for quantification of BMAA in mussels using dansyl chloride derivatization and ultra performance liquid chromatography tandem mass spectrometry
- 2013
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Ingår i: Analytical Methods. - : Royal Society of Chemistry (RSC). - 1759-9660 .- 1759-9679. ; 5:18, s. 4865-4874
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Tidskriftsartikel (refereegranskat)abstract
- A new approach for the detection and quantification of beta-N-methylamino-L-alanine (BMAA) in mussels using chemical derivatization with dansyl chloride and ultra performance liquid chromatography-electrospray ionization-tandem mass spectrometry (UPLC-ESI-MS/MS) is presented. The method, using dansyl chloride as the reagent, is simple, robust and cost efficient. Comparing the fragmentation patterns for derivatized BMAA and its isomer L-2,4-diaminobutyric acid derivatized a selective fragment for the derivatized BMAA was formed m/z 585 > m/z 71. To ensure an actual detection of BMAA, the ion ratio of the daughter ions m/z 71 and m/z 277 was calculated and compared with the calculated mean ion ratio. The method development resulted in a simplified sample preparation excluding solid phase extraction and, instead, performing filtration and dilution of the samples before the derivatization. Validation was performed and the limit of quantification was determined to be 0.15 mu g g(-1) wet mussel homogenate (33 fmol per injection) and the limit of detection was estimated to be 16 ng g(-1) (4 fmol per injection). The intra-and inter-day precisions were within the accepted criteria and the recovery was about 83%. The stability of BMAA in the stock solution was at least 3 months and the stability of derivatized extracts in vials for the quantification was good for 27 days. This is the first quantification method for BMAA in mussels with extensive validation data published and the method was also applied on real mussel samples collected on the west coast of Sweden. The concentrations of BMAA in the mussel samples were determined to be between 0.27 and 1.6 mu g g(-1) wet mussel homogenates.
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| 19. |
- Törnvall, Ulrika
(författare)
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Pinpointing oxidative modifications in proteins-recent advances in analytical methods
- 2010
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Ingår i: Analytical Methods. - : Royal Society of Chemistry (RSC). - 1759-9660 .- 1759-9679. ; 2:11, s. 1638-1650
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Forskningsöversikt (refereegranskat)abstract
- Oxidation is one of the key degradation pathways in proteins and is of relevance to analyze in a wide variety of research disciplines. The types of different modifications occurring during oxidation by reactive oxygen species (ROS) are almost as many as the number of available analytical methods. Protein oxidation in biological samples has traditionally been analyzed by various protein carbonyl assays, sometimes combined with mass spectrometry (MS) for identification of the carbonylated proteins. MS is now increasingly used also for the determination of the exact position of the oxidation in the amino acid sequence, an approach that is aided by recent developments within the field of proteomics. The following review summarizes the effects of ROS on proteins, describes methods for labeling and separation of oxidized proteins in complex mixtures, and provides insight into various MS-based methods to localize the modifications within the protein primary structure. Pitfalls with the different techniques are given, as well as examples from various applications within biological studies, protein therapeutics, plant science, the food industry and industrial biotechnology.
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| 20. |
- Yin, M., et al.
(författare)
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Highly sensitive and selective fiber-optic modal interferometric sensor for detecting trace mercury ion in aqueous solution
- 2012
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Ingår i: Analytical Methods. - : Royal Society of Chemistry (RSC). - 1759-9660 .- 1759-9679. ; 4:5, s. 1292-1297
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Tidskriftsartikel (refereegranskat)abstract
- A novel type of fiber-optic mercury ion (Hg 2+) sensor was prepared by coating poly (N-ethyl-4-vinylpyridinium chloride) (P4VP·HCl) and poly (sodium-p-styrenesulfonate) (PSS) ultrathin film on the surface of a thin-core fiber modal interferometer (TCFMI) with layer-by-layer (LbL) electrostatic self-assembly method. The fabricated TCFMI Hg 2+ sensor exhibits a high selectivity to Hg 2+ and its detection limit and response time are 10 -9 M and 30 s, respectively. The LbL electrostatic self-assembly process is monitored with a quartz crystal microbalance (QCM) and UV-vis spectroscopy for film growth. Atomic force microscopy (AFM) and field emission scanning electron microscopy (FESEM) were used to characterize the morphology of the ultrathin film. Both demonstrated nanoporous film, which is helpful in shortening the response time of the TCFMI Hg 2+ sensor.
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