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Ion Chromatography (ion + chromatography)
Selected AbstractsSimultaneous Determination of Fluorine, Chlorine, Bromine and Iodine in Six Geochemical Reference Materials Using Pyrohydrolysis, Ion Chromatography and Inductively Coupled Plasma-Mass SpectrometryGEOSTANDARDS & GEOANALYTICAL RESEARCH, Issue 4 2009Hélène Balcone-Boissard halogènes; pyrohydrolyse; chromatographie ionique; spectrométrie de masse couplée à une source de plasma induit; matériaux géologiques de référence Concentrations of halogens (fluorine, chlorine, bromine and iodine) were determined in six geochemical reference materials (BHVO-2, GS-N, JG-1, JR-1, JB-1b, JB-2). Halogens were first extracted from powdered samples using a pyrohydrolysis technique, then hydrolysis solutions were analysed by ion chromatography for F and Cl and inductively coupled plasma-mass spectrometry for Br and I. The detection limits in solutions were 100 ,g l,1 for both F and Cl and 10 ng l,1 for Br and I. Considering the extraction procedure, performed on a maximum of 500 mg of sample and producing 100 ml of pyrohydrolysis solution, detection limits in rock samples were 20 mg kg,1 for F and Cl and 2 ,g kg,1 for Br and I. The mean analytical errors on the studied composition ranges were estimated at 10 mg kg,1 for F and Cl, 100 ,g kg,1 for Br and 25 ,g kg,1 for I. The concentration values, based on repeated (generally > 10) sample analysis, were in good agreement generally with published values and narrowed the mean dispersion around mean values. Large dispersions are discussed in terms of samples heterogeneity and contaminations during sample preparation. Basaltic RMs were found to be more suitable for studies of halogen compositions than differentiated rock material, especially granites , the powders of which were heterogeneous in halogens at the 500 mg level. Les concentrations en halogènes (fluor, chlore, brome et iode) on été déterminées dans 6 matériaux géologiques de référence (BHVO-2, GS-N, JG-1, JR-1, JB-1b, JB-2), distribués par le GSJ, l'USGS et le CRPG. Les halogènes étaient d'abord extraits des échantillons, disponibles sous forme de poudre, par pyrohydrolyse. F et Cl sont ensuite analysés par chromatographie ionique, Br et I par spectrométrie de masse couplée à une source de plasma induit. Les limites de détection sont de 100 ,g l,1 pour F et Cl, et de 10 ng l,1 pour Br et I, respectivement. L'extraction des halogènes était réalisée sur 500 mg de poudre de roche, produisant 100 ml de solution d'extraction. Ainsi, pour les échantillons de roche, les limites de détection étaient de 20 mg kg,1 pour F et Cl, et 2 ,g kg,1 pour Br et I. L'erreur analytique moyenne sur la gamme de concentration étudiée est estimée à 10 mg kg,1 pour F et Cl, 100 ,g kg,1 pour Br et 25 ,g kg,1 pour I. Les valeurs de concentrations données, obtenues par l'analyse répétée (> 10) du même échantillon étaient en accord avec les valeurs reportées dans la littérature. Elles présentent en général une plus faible dispersion autour de la valeur moyenne. Dans le cas d'une importante dispersion des résultats, celle-ci est discutée en terme d'hétérogénéité de l'échantillon analysé et de contamination durant la préparation du matériel de référence. Les échantillons de référence de composition basaltique se révèlent être plus appropriés pour étudier les compositions en halogènes que les matériaux correspondant à des roches différenciées, en particulier des granites dont la distribution en halogènes apparaît hétérogène dans les poudres à l'échelle d'un aliquot de 500 mg. [source] A theoretical explanation for the retention mechanism of ion exclusion chromatographyJOURNAL OF SEPARATION SCIENCE, JSS, Issue 17 2003Bronis, aw K. G Abstract Ion Exclusion Chromatography is classically used for the separation of weak acid anions. Dilute strong acids (e.g. sulphuric or perchloric acid) or just water are used as eluents. To increase the exclusion effect, strong cation exchangers, characterized by high concentration of functional groups, are applied. The inner column volume of commercially available columns is increased by increasing their size in comparison to traditional ones (usually 300×7.8 mm ID). The description of the retention mechanism of this technique implicitly assumes that both mobile and stationary phases are typical aqueous solutions, and their dielectric constants are thus equal. This equality implies the equality of solute dissociation constants in both phases. Another implicit assumption is that the dead- and inner volumes of the column are constant, and independent of the mobile phase composition. The present paper shows that stationary and mobile phases are generally characterized by different physicochemical parameters. Thus, they cannot be considered as regular aqueous solutions. Additionally, we show that weak cation exchanger resins, which are characterized by a relatively small concentration of the functional groups, and weak acid based buffers can also be used in IEC. This would expand the possible applications of this method and enable, for example, the separation of strong acids (anions). The influence of ionic strength on the retention and dead- and inner column volumes is also discussed. Finally we also briefly describe the retention mechanism of Electrostatic Ion Chromatography. [source] Indirect laser-induced fluorescence detection for capillary electrophoresis using a frequency-doubled diode laserELECTROPHORESIS, Issue 3 2003Natalia Ragozina Abstract A blue (452 nm) frequency-doubled diode laser with a quasi-cw optical output power of 10 ,W is used for indirect laser-induced fluorescence detection in combination with the capillary electrophoretic separation of inorganic anions. As fluorescing probe ion the anion of 8-hydroxypyrene-1,3,6-trisulfonic acid (HPTS) was selected having an absorption maximum of 454 nm in alkaline medium. Employing a capillary coated with linear acrylamide, baseline separation of eight inorganic anions was possible within 5 min. With a separation buffer containing 50 ,mol·L -1 HPTS and 10 mmol·L -1 lysine the limits of detection for sulfate, nitrite, nitrate, azide, thiocyanate, and chlorate were between 0.9 and 4.7 ,mol·L -1. Separation of chloride and sulfate was achieved by adding 0.25 mmol·L -1 calcium hydroxide to the separation buffer. Inorganic anions in several mineral and tap water samples have been determined with the technique developed and results are compared to data obtained by ion chromatography in combination with conductivity detection after conductivity suppression. [source] Perchlorate assessment of the Nakdong and Yeongsan watersheds, Republic of KoreaENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 7 2007Oscar Quiñones Abstract The objective of the present study was to conduct a preliminary assessment for perchlorate in surface water, drinking water, and wastewater treatment plant effluent samples obtained from the Nakdong and Yeongsan watersheds in the Republic of Korea. Samples were analyzed for perchlorate using ion chromatography with suppressed conductivity detection (IC-CD) and/or liquid chromatography with tandem mass spectrometry detection (LC-MS/MS). Method reporting limits were 5.0 ,g/L for IC-CD and 0.05 ,g/L for LC-MS/MS analysis. At perchlorate levels above 5.0 ,g/L, IC-CD and LC-MS/MS provided comparable results. The levels of perchlorate detected in the samples procured from the Yeongsan watershed were <5.0 ,g/L in each case. However, Nakdong watershed samples contained perchlorate at levels up to 60 ,g/L. The highest concentrations of perchlorate were found in surface water samples, although drinking water contained perchlorate at concentrations up to 35 ,g/L. In a subset of samples analyzed by LC-MS/MS, chlorate and bromate also were detected at concentrations ranging from <0.10 to 44 ,g/L and <0.10 to 2.6 ,g/L, respectively. To the best of the authors' knowledge, this is the first perchlorate assessment reported for water sources in the Republic of Korea. [source] Ammonium fluoride extraction for determining inorganic sulphur in acid forest soilsEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 2 2000J. Prietzel Summary Current methods for determining inorganic sulphur (S) in aerated mineral soil horizons often result in underestimates. To overcome this defect we developed a new method combining a batch extraction with 0.5 m NH4F solution at a soil:solution ratio of 1:5 with a subsequent analysis of the mobilized SO42, by ion chromatography. The ammonium fluoride extraction enables us to characterize inorganic sulphate in non-calcareous forest soils. It is more efficient than conventional procedures in which inorganic S is extracted with phosphate or bicarbonate solution. In contrast to the extraction with strongly alkaline reagents (NaOH, KOH, LiOH), the NH4+,NH3 buffer system in NH4F prevents the pH of the suspension from exceeding 9.0 and thus the undesired conversion of organic S into SO42, by auto-oxidation and hydrolysis of ester sulphate. In a comparison we demonstrated that the inorganic S in six German forest soils is underestimated by up to 50% or 200 kg S ha,1 in the uppermost 60 cm, if it is assessed by extraction with 0.016 m KH2PO4 or 0.5 m NaHCO3 instead of 0.5 m NH4F. Conversely, the pool of ester sulphate is overestimated almost threefold. [source] Simultaneous Determination of Fluorine, Chlorine, Bromine and Iodine in Six Geochemical Reference Materials Using Pyrohydrolysis, Ion Chromatography and Inductively Coupled Plasma-Mass SpectrometryGEOSTANDARDS & GEOANALYTICAL RESEARCH, Issue 4 2009Hélène Balcone-Boissard halogènes; pyrohydrolyse; chromatographie ionique; spectrométrie de masse couplée à une source de plasma induit; matériaux géologiques de référence Concentrations of halogens (fluorine, chlorine, bromine and iodine) were determined in six geochemical reference materials (BHVO-2, GS-N, JG-1, JR-1, JB-1b, JB-2). Halogens were first extracted from powdered samples using a pyrohydrolysis technique, then hydrolysis solutions were analysed by ion chromatography for F and Cl and inductively coupled plasma-mass spectrometry for Br and I. The detection limits in solutions were 100 ,g l,1 for both F and Cl and 10 ng l,1 for Br and I. Considering the extraction procedure, performed on a maximum of 500 mg of sample and producing 100 ml of pyrohydrolysis solution, detection limits in rock samples were 20 mg kg,1 for F and Cl and 2 ,g kg,1 for Br and I. The mean analytical errors on the studied composition ranges were estimated at 10 mg kg,1 for F and Cl, 100 ,g kg,1 for Br and 25 ,g kg,1 for I. The concentration values, based on repeated (generally > 10) sample analysis, were in good agreement generally with published values and narrowed the mean dispersion around mean values. Large dispersions are discussed in terms of samples heterogeneity and contaminations during sample preparation. Basaltic RMs were found to be more suitable for studies of halogen compositions than differentiated rock material, especially granites , the powders of which were heterogeneous in halogens at the 500 mg level. Les concentrations en halogènes (fluor, chlore, brome et iode) on été déterminées dans 6 matériaux géologiques de référence (BHVO-2, GS-N, JG-1, JR-1, JB-1b, JB-2), distribués par le GSJ, l'USGS et le CRPG. Les halogènes étaient d'abord extraits des échantillons, disponibles sous forme de poudre, par pyrohydrolyse. F et Cl sont ensuite analysés par chromatographie ionique, Br et I par spectrométrie de masse couplée à une source de plasma induit. Les limites de détection sont de 100 ,g l,1 pour F et Cl, et de 10 ng l,1 pour Br et I, respectivement. L'extraction des halogènes était réalisée sur 500 mg de poudre de roche, produisant 100 ml de solution d'extraction. Ainsi, pour les échantillons de roche, les limites de détection étaient de 20 mg kg,1 pour F et Cl, et 2 ,g kg,1 pour Br et I. L'erreur analytique moyenne sur la gamme de concentration étudiée est estimée à 10 mg kg,1 pour F et Cl, 100 ,g kg,1 pour Br et 25 ,g kg,1 pour I. Les valeurs de concentrations données, obtenues par l'analyse répétée (> 10) du même échantillon étaient en accord avec les valeurs reportées dans la littérature. Elles présentent en général une plus faible dispersion autour de la valeur moyenne. Dans le cas d'une importante dispersion des résultats, celle-ci est discutée en terme d'hétérogénéité de l'échantillon analysé et de contamination durant la préparation du matériel de référence. Les échantillons de référence de composition basaltique se révèlent être plus appropriés pour étudier les compositions en halogènes que les matériaux correspondant à des roches différenciées, en particulier des granites dont la distribution en halogènes apparaît hétérogène dans les poudres à l'échelle d'un aliquot de 500 mg. [source] Simultaneous analyses and applications of multiple fluorobenzoate and halide tracers in hydrologic studiesHYDROLOGICAL PROCESSES, Issue 14 2005Qinhong Hu Abstract An analytical method that employs ion chromatography has been developed to exploit the use of fluorobenzoic acids (FBAs) and halides more fully as hydrologic tracers. In a single run, this reliable, sensitive, and robust method can simultaneously separate and quantify halides (fluoride, chloride, bromide, and iodide) and up to seven FBAs from other common groundwater constituents (e.g. nitrate and sulphate). The usefulness of this analytical method is demonstrated in both field and laboratory tracer experiments. The field study examines the hydrologic response of fractures and the matrix to different flow rates and the contribution of matrix diffusion in chemical transport. Laboratory tracer experiments with eight geologic media from across the USA,mostly from Department of Energy facilities where groundwater contamination is prevalent and where subsurface characterization employing tracers has been ongoing or is in need,reveal several insights about tracer transport behaviour: (1) bromide and FBAs are not always transported conservatively; (2) the delayed transport of these anionic tracers is likely related to geologic media characteristics, such as organic matter, pH, iron oxide content, and clay mineralogy; (3) use of iodine as a hydrologic tracer should take into account the different sorption behaviours of iodide and iodate and the possible conversion of iodine's initial chemical form; (4) the transport behaviour of potential FBA and halide tracers under relevant geochemical conditions should be evaluated before beginning ambitious, large-scale field tracer experiments. Copyright © 2005 John Wiley & Sons, Ltd. [source] Application of different training methodologies for the development of a back propagation artificial neural network retention model in ion chromatographyJOURNAL OF CHEMOMETRICS, Issue 2 2008Tomislav Bolan Abstract The reliability of predicted separations in ion chromatography depends mainly on the accuracy of retention predictions. Any model able to improve this accuracy will yield predicted optimal separations closer to the reality. In this work artificial neural networks were used for retention modeling of void peak, fluoride, chlorite, chloride, chlorate, nitrate and sulfate. In order to increase performance characteristics of the developed model, different training methodologies were applied and discussed. Furthermore, the number of neurons in hidden layer, activation function and number of experimental data used for building the model were optimized in terms of decreasing the experimental effort without disruption of performance characteristics. This resulted in the superior predictive ability of developed retention model (average of relative error is 0.4533%). Copyright © 2008 John Wiley & Sons, Ltd. [source] Recent developments in the high-performance chelation ion chromatography of trace metalsJOURNAL OF SEPARATION SCIENCE, JSS, Issue 11 2007Pavel N. Nesterenko Abstract There have been a number of significant developments in the high-performance chelation ion chromatography (HPCIC) of trace metals in recent years. This review focuses on these developments, while giving important information on the fundamental parameters controlling the chelation sorption mechanism, including type of chelating group, stability constants, kinetics, and column temperature. The discussion pays particular attention to the types and properties of efficient chelating stationary phases which have been fabricated for certain groups of metals. The review also describes a number of major improvements in postcolumn reaction detection including the use of the latest reagents and noise reduction strategies to improve sensitivity and reduce LOD. In the final section, an indication of the applicability of HPCIC to a range of complex sample types is given with some key examples and chromatograms using the latest high-efficiency chelating phases. [source] Highly automated and fast determination of raffinose family oligosaccharides in Lupinus seeds using pressurized liquid extraction and high-performance anion-exchange chromatography with pulsed amperometric detectionJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 11 2008David Bansleben Abstract BACKGROUND: Taking into account several requirements for the determination of raffinose family oligosaccharides (RFOs) from Lupinus seeds,e.g., conducting plant breeding projects or food product development,a reasonable combination of efficient automated sample preparation and reliable analysis need to be developed and validated. RESULTS: In this regard pressurized liquid extraction was applied to extract the RFOs from ground and defatted lupin flour. Compared to many other publications, no further pretreatment, such as protein precipitation, was necessary to obtain satisfactory results applying ion chromatography with pulsed amperometric detection. The oligosaccharide content for the examined Lupinus albus samples were in the range 5.19,9.25 g kg,1 and for Lupinus angustifolius RFOs 3.49,4.75 g kg,1. Stachyose has always been the main component followed by raffinose and verbascose. CONCLUSION: The developed sample preparation and analytical method is suited to quantify raffinose, stachyose, verbascose and the disaccharide sucrose and, owing to a high degree of automation for sample preparation and relatively short analysis times by pretty peak separation, particularly high sample numbers can be accomplished. Copyright © 2008 Society of Chemical Industry [source] Pitting corrosion on 316L pipes in terephthalic acid (TA) dryerMATERIALS AND CORROSION/WERKSTOFFE UND KORROSION, Issue 11 2009Y. Gong Abstract Grade 316L is a type of austenitic stainless steel with ultra-low carbon content and it exhibits superior corrosion resistance. However, pitting is always observed in 316L steel when it is exposed to media containing halide ions. In the present study, we found that in the presence of acetate acid (HAc) containing chloride or bromide ions, pitting occurred on the surface of the rotary steam pipes with the matrix material of 316L steel in terephthalic acid (TA) dryer. In order to identify the causes of the failure, metallographic structures and chemical compositions of the matrix material were inspected by an optical microscope (OM) and a photoelectric direct reading spectrometer. Beside these, scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) as well as ion chromatography (IC) were used to analyze the micromorphologies of the corrosion pits and the chemical compositions of the corrosion deposits within them. Analysis of the results revealed the sources of halide ions and the factors accelerating the corrosion rate. Beside these, detailed mechanisms of pitting were discussed and six out of all the seven theoretical morphologies of pitting features were obtained in practice. [source] Analysis of carbohydrates and amino acids in vegetable waste waters by ion chromatographyPHYTOCHEMICAL ANALYSIS, Issue 2 2003Michele Arienzo Abstract High-performance anion exchange chromatography coupled with pulsed amperometric detection was used for the quantitative determination of total and free sugars in olive oil mill waste waters (OMWW). Automated amino acid ion chromatography was employed to analyse total and free amino acids in the same OMWW. Sugars were analysed in samples pre-purified by means of a three-step purification procedure involving: (i) methanol precipitation of OMWW; (ii) dialysis of the obtained solid and liquid fractions; and (iii) chromatographic purification on RP18 phase followed by Amberlite resin. The amino acids were determined directly in samples obtained from the first two steps performed for sugar analysis. The analysis carried out with the reported methodologies allowed the quantitative determination of total sugars and amino acids and the differentiation between their free and bound forms. The sugars determined were arabinose, fructose, galactose, glucose, rhamnose, xylose, galacturonic and glucuronic acids, and the amino acids were Asp, Glu, Thr, Ser, Pro, Gly, Ala, Val, Met, Ile, Leu, Tyr, Phe, Lys, His, Arg and Cys. Asn, Gln, and Trp were not detected. The technological, biotechnological and environmental advantages arising from this analytical methodology applied to OMWW are briefly discussed. Copyright © 2003 John Wiley & Sons, Ltd. [source] High-resolution extracted ion chromatography, a new tool for metabolomics and lipidomics using a second-generation orbitrap mass spectrometerRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 10 2009Albert Koulman Most analytical methods in metabolomics are based on one of two strategies. The first strategy is aimed at specifically analysing a limited number of known metabolites or compound classes. Alternatively, an unbiased approach can be used for profiling as many features as possible in a given metabolome without prior knowledge of the identity of these features. Using high-resolution mass spectrometry with instruments capable of measuring m/z ratios with sufficiently low mass measurement uncertainties and simultaneous high scan speeds, it is possible to combine these two strategies, allowing unbiased profiling of biological samples and targeted analysis of specific compounds at the same time without compromises. Such high mass accuracy and mass resolving power reduces the number of candidate metabolites occupying the same retention time and m/z ratio space to a minimum. In this study, we demonstrate how targeted analysis of phospholipids as well as unbiased profiling is achievable using a benchtop orbitrap instrument after high-speed reversed-phase chromatography. The ability to apply both strategies in one experiment is an important step forward in comprehensive analysis of the metabolome. Copyright © 2009 John Wiley & Sons, Ltd. [source] Determination of stable carbon isotopes of organic acids and carbonaceous aerosols in the atmosphereRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 15 2006R. Fisseha A wet oxidation method for the compound-specific determination of stable carbon isotopes (,13C) of organic acids in the gas and aerosol phase, as well as of water-soluble organic carbon (WSOC), is presented. Sampling of the organic acids was done using a wet effluent diffusion denuder/aerosol collector (WEDD/AC) coupled to an ion chromatography (IC) system. The method allows for compound-specific stable carbon isotope analysis by collecting different fractions of organic acids at the end of the IC system using a fraction collector. ,13C analyses of organic acids were conducted by oxidizing the organic acids with sodium persulfate at a temperature of 100°C and determining the ,13C value of the resulting carbon dioxide (CO2) with an isotope ratio mass spectrometer. In addition, analysis of ,13C of the WSOC was performed for particulate carbon collected on aerosol filters. The WSOC was extracted from the filters using ultrapure water (MQ water), and the dissolved organic carbon was oxidized to CO2 using the oxidation method. The wet oxidation method has an accuracy of 0.5, with a precision of ±0.4, and provides a quantitative result for organic carbon with a detection limit of 150,ng of carbon. Copyright © 2006 John Wiley & Sons, Ltd. [source] Metabolism of dimethylarsinic acid in rats: production of unidentified metabolites in vivoAPPLIED ORGANOMETALLIC CHEMISTRY, Issue 6 2001Kaoru Yoshida Abstract Our previous study revealed that two unidentified metabolites, M-1 and M-2, were excreted in urine after long-term oral administration of dimethylarsinic acid (DMA), the main metabolite of inorganic arsenic. In the present study, we attempted to clarify the mechanism of production of these unknown metabolites. Male F344/DuCrj rats were administered a single dose of DMA (50,mg kg,1) orally or intraperitoneally with or without pretreatment with L -buthionine-SR-sulfoximine (BSO), which inhibits glutathione (GSH) synthesis. Urine was collected by forced urination at various time points after administration of DMA. Arsenic metabolites in urine were analyzed by ion chromatography with inductively coupled plasma mass spectrometry (IC,ICP-MS). The unidentified metabolites M-1 and M-2 were excreted later than elimination of DMA and trimethylarsine oxide (TMAO). GSH depletion decreased in TMAO elimination, suggesting that GSH plays important roles in the methylation of DMA to TMAO in rats. There was no difference in the amount of production of either M-1 or M-2 between BSO-pretreated rats and controls, suggesting that M-1 and M-2 cannot be formed during methylation in the liver. The amounts of elimination of M-1 and M-2 were less after intraperitoneal administration than after oral administration. Male F344/DuCrj rats were given 100,mg As l,1 DMA via drinking water for 20 weeks. Urine and feces were collected forcibly and were analyzed by IC,ICP-MS. A new unidentified metabolite, M-3, was detected only in feces as a metabolite of DMA after 20 weeks exposure to DMA, although M-1 and M-2 were found in both urine and feces. The unidentified metabolites M-1, M-2, and M-3 were excreted mainly as fecal metabolites along with unmetabolized DMA. This finding also suggests that M-1, M-2, and M-3 might be produced in the intestinal tract. Copyright © 2001 John Wiley & Sons, Ltd. [source] Enteric bacteria may play a role in mammalian arsenic metabolismAPPLIED ORGANOMETALLIC CHEMISTRY, Issue 6 2001Koichi Kuroda Abstract The cecal content of rats administered dimethylarsinic acid for 6 months via drinking water was cultured in GAM medium with 10,mg l,1 of dimethylarsinic acid. Arsenic compounds in the culture were analyzed by ion chromatography with inductively coupled plasma mass spectrometry (IC,ICP-MS). Dimethylarsinic acid was metabolized. Two bacterial Escherichia coli strains, A3-4 and A3-6, were isolated from the culture. These strains metabolized dimethylarsinic acid and yielded two unidentified arsenic compounds, M-2 and M-3. A3-6 methylated dimethylarsinic acid to trimethylarsine oxide. Both strains metabolized trimethylarsine oxide and yielded an unidentified arsenic compound, M-1. These unknown arsenic compounds were the same compounds as detected in the urine and the feces of rats administered dimethylarsinic acid. The strains reduced arsenate to arsenite efficiently. Cysteine was required for metabolism of dimethylarsinic acid by these bacteria, but glutathione was not required. These results strongly suggested that the intestinal bacteria have a different arsenic metabolism from that in mammals and that they may play a possible role in mammalian arsenic metabolism. Copyright © 2001 John Wiley & Sons, Ltd. [source] Recovering Ga(III) from coordination complexes using pyridine 2,6-dicarboxylic acid chelation ion chromatographyBIOMEDICAL CHROMATOGRAPHY, Issue 9 2010K. Staff Abstract Ion exchange chelation chromatography is an effective means to extract metals from coordination complexes and biological samples; however there is a lack of data to verify the nature of metal complexes that can be successfully analysed using such a procedure. The aim of this study was to assess the capability of pyridine 2,6-dicarboxylic acid (PDCA) to extract and quantify Ga(III) from a range of environments using standard liquid chromatography apparatus. The PDCA chelation method generated a single Ga(III) peak with a retention time of 2.55 ± 0.02 min, a precision of <2% and a limit of detection of 110 ,M. Ga(III) hydroxide complexes (highest stability constant 15.66) were used to successfully cross-validate the chelation method with inductively coupled plasma mass spectrometry. The PDCA assay extracted 96.9 ± 1.2% of the spiked Ga(III) from porcine mucus and 100.7 ± 2.7% from a citrate complex (stability constant 10.02), but only ca 50% from an EDTA complex (stability constant 22.01). These data suggest that PDCA chelation can be considered a suitable alternative to inductively coupled plasma mass spectrometry for Ga(III) quantification from all but the most strongly bound coordinated complexes i.e. a stability constant of <15. Copyright © 2010 John Wiley & Sons, Ltd. [source] Characterization and determination of chlorophacinone in plasma by ion chromatography coupled with ion trap electrospray ionization mass spectrometryBIOMEDICAL CHROMATOGRAPHY, Issue 5 2009Xiao-kun OuYang Abstract Plasmatic chlorophacinone is commonly measured with liquid chromatographic assay, which convenient but lacks sensitivity and selectivity and usually requires ion pair reagents to reduce the chromatographic tailed peak. In this paper, a novel method using eluent generator reagent-free ion chromatography coupled with electrospray ionization ion trap mass spectrometric detection for the determination of chlorophacinone in plasma has been developed. After samples were extracted with 10% (v/v) methanol in acetonitrile and cleaned by solid-phase extraction, chromatographic separation was performed on an IonPac® AS11 analytical column (250 × 4.0 mm) using 40.0 mmol/L KOH containing 10% (v/v) methanol as organic modifier. Quantification was performed by negative electrospray ionization in multiple reaction monitoring mode. The transition m/z 373 , 201 was for the quantification ion; the transitions m/z 373 , 172 and m/z 373 , 145, as well as the isotope ions m/z 375 and m/z 203, were for the qualitative ions. All the method parameters were validated. It was confirmed that this method can be used in clinical diagnosis and forensic toxicology. Copyright © 2008 John Wiley & Sons, Ltd. [source] Effect of varying feedstock,pretreatment chemistry combinations on the formation and accumulation of potentially inhibitory degradation products in biomass hydrolysatesBIOTECHNOLOGY & BIOENGINEERING, Issue 3 2010Bowen Du Abstract A variety of potentially inhibitory degradation products are produced during pretreatment of lignocellulosic biomass. Qualitative and quantitative interrogation of pretreatment hydrolysates is paramount to identifying potential correlations between pretreatment chemistries and microbial inhibition in downstream bioconversion processes. In the present study, corn stover, poplar, and pine feedstocks were pretreated under eight different chemical conditions, which are representative of leading pretreatment processes. Pretreatment processes included: 0.7% H2SO4, 0.07% H2SO4, liquid hot water, neutral buffer solution, aqueous ammonia, lime, lime with oxygen pressurization, and wet oxidation. Forty lignocellulosic degradation products resulting from pretreatment were analyzed using high performance liquid chromatography in combination with UV spectroscopy or tandem mass spectrometry detection (HPLC-PDA-MS/MS) and ion chromatography (IC). Of these compounds, several have been reported to be inhibitory, including furfural, hydroxymethyl furfural, ferulic acid, 3,4-dihydroxybenzaldehyde, syringic acid among others. Formation and accumulation of monitored compounds in hydrolysates is demonstrated to be a function of both the feedstock and pretreatment conditions utilized. Biotechnol. Bioeng. 2010;107: 430,440. © 2010 Wiley Periodicals, Inc. [source] Preparation of LLDPE/MgAl-LDH Exfoliation Nanocomposites with Enhanced Thermal Properties by Melt IntercalationCHINESE JOURNAL OF CHEMISTRY, Issue 10 2006Long-Chao Du Abstract The interlayer surface of MgAl layered double hydroxide (MgAl-LDH) was modified by exchanging about half of the interlayer nitrate anions by dodecyl sulfate anions (DS) to get MgAl(H-DS) LDH, and then the MgAl(H-DS) was melt intercalated by LLDPE to get the LLDPE/MgAl-LDH exfoliation nanocomposites. The samples were characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), ion chromatography, transmission electron microscopy (TEM), and thermogravimetry analysis (TGA). The nanoscale dispersion of MgAl-LDH layers in the LLDPE matrix was verified by the disappearance of (00l) XRD reflection of the modified MgAl-LDH and by the TEM observation. The TGA profiles of LLDPE/MgAl-LDH nanocomposites show a faster charring process between 210 and 370 °C and a higher thermal stability above 370 °C than LLDPE. The decomposition temperature of the nanocomposites with 10 wt% MgAl(H-DS) can be 42 °C higher than that of LLDPE at 40% weight loss. [source] | |||||||||||||||||||