Suchergebnisse

An introduction to pH Measurement : estimating the degree of purity of snow; Measuring soil pH; Introduction to ion chromatography -- Introduction to the visible spectrophotometer -- Visible spectrophotometric determination of trace levels of iron in groundwater -- Spectrophotometric determination of phosphorus in eutrophicated surface water -- Determination of anionic surfactants by mini-liquid-liquid extraction (MINI-LLE) in an industrial wastewater effluent using ion pairing with methylene blue -- Comparison of ultraviolet and infrared absorption spectra of chemically similar organic compounds -- Determination of oil and grease and of total petroleum hydrocarbons in wastewater via reversed-phase solid-phase extraction techniques (RP-SPE) and quantitative Fourier-transform infrared (FTIR) spectroscopy -- Determination of the degree of hardness in various sources of groundwater using flame atomic absorption spectroscopy -- Determination of lead in drinking water using graphite furnace atomic absorption spectroscopy (GFAA) : external standard vs. standard addition calibration mode -- A comparison of soil types via a quantitative determination of the chromium content using visible spectrophotometry and flame atomic absorption spectroscopy or inductively coupled plasma-optical emission spectrometry -- Data acquisition and instrument control using the Turbochrom chromatography software. an introduction to high-performance liquid chromatography (HPLC) : evaluating those experimental parameters that influence separations -- Identifying the ubiquitous phthalate esters in the environment using HPLC, photodiode array detection, and confirmation by GC-MS -- An introduction to gas chromatography : evaluating experimental parameters that influence gas chromatographic performance -- Screening for the presence of BTEX in wastewater using liquid-liquid extraction (LLE) and gas chromatography : screening for THMs in chlorine-disinfected drinking water using static headspace (HS) gas chromatography -- Determination of priority pollutant volatile organic compounds (VOCs) in gasoline-contaminated groundwater using static headspace (HS) and solid-phase microextraction headspace (SPME-HS) and gas chromatography -- Determination of the herbicide residue Trifluralin in chemically treated lawn soil by gas chromatography using reversed-phase solid-phase extraction (RP-SPE) sample prep techniques -- Determination of priority pollutant semivolatile organochlorine pesticides : a comparison of mini-liquid-liquid and reversed-phase solid-phase extraction techniques -- Determination of priority pollutant polycyclic aromatic hydrocarbons (PAHs) in contaminated soil using RPHPLC-PDA with wavelength programming -- Determination of inorganic anions using ion chromatography (IC) : anion exchange IC with suppressed conductivity detection.

Currently, 80 to 85% of leather is tanned with chrome. This process allows to obtain excellent physico-mechanical properties with optimum economic conditions. The chromium salts in trivalent form used in the manufacturing of leather are not harmful; however under some conditions and associated with other substances, trivalent chromium can be transformed into hexavalent chromium, highly allergenic and potentially harmful to the health of the consumer. Since 1st May 2015, the presence of hexavalent chromium in leather is subject to European legislation; the hexavalent chromium content must not exceed 3 mg/kg of the total dry weight of leather (REACh ANNEX 17, § 47). To date, a great amount of research has been done and initial hypothesis have been able to explain the formation of hexavalent chromium in leather. The objective of this research project was to rationalize and to deal with these various studies in order to understand this problem in more detail. In this thesis project, the introduction of ion chromatography has improved the specificity and reliability of the analysis method for the determination of hexavalent chromium. Secondly, the influence of leather composition (fat liquor, iodine value, pH, total chromium and extractible chromium) on the formation of hexavalent chromium in leather was studied. The objective was to explain the potential oxidation mechanisms of trivalent chromium (in hexavalent chromium). The third part of this study deals with environmental factors (temperature, relative humidity, light and duration of exposure), leather manufacturing conditions or the life cycle of leather (transport, transformation into finished product, consumer use). The aim was to determine the impact of these parameters on the formation of hexavalent chromium. To conclude, an "artificial" ageing method representing the natural evolution of leather, and which corresponds to the characteristics and the nature of the leather, has been proposed ; Actuellement, 80 à 85% des cuirs sont tannés au chrome. Ce procédé ...

Based on a symposium sponsored by the Environmental Division of the American Chemical Society, Perchlorate in the Environment is the first comprehensive book to address perchlorate as a potable water contaminant. The two main topics are: analytical chemistry (focusing on ion chromatography and electrospray ionization mass spectrometry), and treatment or remediation. Also included are topics such as ion exchange, phytoremediation, bacterial reduction of perchlorate, bioreactors, and in situ bioremediation. To provide complete coverage, background chapters on fundamental chemistry, toxicology, and reulatory issues are also included. The authors are environmental consultants, government researchers, industry experts, and university professors from a wide array of disciplines

While the knowledge of plant metabolomes has increased in the last few years, their response to the presence of toxicants is still poorly understood. Here, we analyse the metabolomic changes in Japanese rice (Oryza sativa var. Japonica) upon exposure to heavy metals (Cd(ii) and Cu(ii)) in concentrations from 10 to 1000 μM. After harvesting, rice metabolites were extracted from aerial parts of the plants and analysed by HPLC (HILIC TSK gel amide-80 column) coupled to a mass spectrometer quadrupole-Orbitrap (Q-Exactive). Full scan and all ion fragmentation (AIF) mass spectrometry modes were used during the analysis. The proposed untargeted metabolomics data analysis strategy is based on the application of the multivariate curve resolution alternating least squares (MCR-ALS) method for feature detection, allowing the simultaneous resolution of pure chromatographic profiles and mass spectra of all metabolites present in the analysed rice extracts. All-ion fragmentation data were used to confirm the identification of MCR-ALS resolved metabolites. A total of 112 metabolites were detected, and 97 of them were subsequently identified and confirmed. Pathway analysis of the observed metabolic changes suggested an underlying similarity of the responses of the plant to Cd(ii) and Cu(ii), although the former treatment appeared to be the more severe of the two. In both cases, secondary metabolism and amino acid-, purine-, carbon- and glycerolipid-metabolism pathways were affected, in a pattern consistent with reduction in plant growth and/or photosynthetic capacity and with induction of defence mechanisms to reduce cell damage. © The Royal Society of Chemistry 2017. ; The research leading to these results has received funding from the European Research Council under the European Union's Seventh Framework Programme (FP/2007-2013)/ERC Grant Agreement no. 320737. The authors would like to thank Center for Research in Agricultural Genomics (CRAG) for kindly supplying Japanese rice seeds. ; Peer reviewed

Currently, 80 to 85% of leather is tanned with chrome. This process allows to obtain excellent physico-mechanical properties with optimum economic conditions. The chromium salts in trivalent form used in the manufacturing of leather are not harmful; however under some conditions and associated with other substances, trivalent chromium can be transformed into hexavalent chromium, highly allergenic and potentially harmful to the health of the consumer. Since 1st May 2015, the presence of hexavalent chromium in leather is subject to European legislation; the hexavalent chromium content must not exceed 3 mg/kg of the total dry weight of leather (REACh ANNEX 17, § 47). To date, a great amount of research has been done and initial hypothesis have been able to explain the formation of hexavalent chromium in leather. The objective of this research project was to rationalize and to deal with these various studies in order to understand this problem in more detail. In this thesis project, the introduction of ion chromatography has improved the specificity and reliability of the analysis method for the determination of hexavalent chromium. Secondly, the influence of leather composition (fat liquor, iodine value, pH, total chromium and extractible chromium) on the formation of hexavalent chromium in leather was studied. The objective was to explain the potential oxidation mechanisms of trivalent chromium (in hexavalent chromium). The third part of this study deals with environmental factors (temperature, relative humidity, light and duration of exposure), leather manufacturing conditions or the life cycle of leather (transport, transformation into finished product, consumer use). The aim was to determine the impact of these parameters on the formation of hexavalent chromium. To conclude, an "artificial" ageing method representing the natural evolution of leather, and which corresponds to the characteristics and the nature of the leather, has been proposed ; Actuellement, 80 à 85% des cuirs sont tannés au chrome. Ce procédé permet d'obtenir d'excellentes propriétés physico-mécaniques dans des conditions économiques optimales. Les sels de chrome sous forme trivalente utilisés lors de la fabrication du cuir ne sont pas nocifs; cependant sous certaines conditions et associés à d'autres substances, le chrome trivalent peut se transformer en chrome hexavalent, très allergisant et pouvant s'avérer dangereux pour la santé du consommateur. Depuis le 1er mai 2015, la présence de chrome hexavalent dans le cuir est soumise à la législation européenne; la teneur en chrome hexavalent ne doit pas excéder plus de 3 mg/kg de poids sec total du cuir (REACh ANNEXE 17, §47). A ce jour, de nombreux travaux de recherche ont été réalisés et des premières hypothèses ont été avancées pour expliquer la formation du chrome hexavalent dans le cuir. L'objectif de ce projet de recherche a été de rationaliser et d'approfondir ces différentes études pour essayer de mieux appréhender cette problématique. Ce projet de thèse a permis d'améliorer la spécificité et la fiabilité la méthode d'analyse pour la détermination de la teneur en chrome hexavalent en introduisant la chromatographie ionique. Ensuite, l'influence de la composition du cuir (matière grasse, indice d'iode, pH, chrome total et chrome extractible) sur la formation de chrome hexavalent dans le cuir a été étudiée afin d'expliquer l'origine et d'éventuels mécanismes d'oxydation du chrome trivalent (en chrome hexavalent). Enfin, cette étude s'est intéressée aux facteurs environnementaux (température, humidité relative, lumière et durée d'exposition), aux conditions de fabrication du cuir ou encore au cycle de vie du cuir (transport, transformation en produit fini, utilisation par le consommateur) afin de déterminer l'impact de ces paramètres sur la formation du chrome hexavalent. A l'issue de ce travail, une méthode de vieillissement "artificiel" représentative de l'évolution réelle d'un cuir a été proposée, et ce quelles que soient les caractéristiques et la nature du cuir

Analytical strategies for screening, quantitation and confirmation of a group of 100 pesticides in fruit and vegetable samples by LC-MS and LC-MS/MS were developed. The pesticides studied belong to different chemical families of herbicides, insecticides and fungicides. A selection of some degradation products was also included. Chromatographic separation was performed using a Zorbax Eclipse XDB-C8 column (150 mm × 4.6 mm and 5 µm particle size), and gradient elution with acetonitrile-water (both with 0.1% formic acid) as mobile phase. LC-MS/MS using highly-selective selected reaction monitoring (H-SRM) acquisition mode monitoring two transitions for each compound showed to be the most sensitive methodology. Quantitation was carried out using matrix-matched standard calibration and good linearity of response was demonstrated (r > 0.998). Limits of detection (by acquiring two transitions and with the ion-ratio requirements) ranged between 0.01 and 20 µg/kg were obtained. So, in general, the sensitivity achieved meets the maximum residue levels (MRLs) established by the European Union regulation for food monitoring programs. Pesticide confirmation was carried out following European Union guidelines. In order to prevent false-positives, further confirmatory strategies were proposed. LC-MS in highly-selective selected ion monitoring (H-SIM) mode with accurate mass measurement was used to obtain an orthogonal criterion (exact mass) for confirmation. Accurate mass measurements were always bellow 0.9 mDa for almost all pesticides studied (similar to those described with TOF instruments). A user reversed energy ramp (RER) product ion scan spectra library was generated by means of a data dependent analysis for routine library searching of pesticides. The combination of LC-MS/MS in H-SRM mode and the generation of the RER product ion scan spectra and library search were then used to achieve further confirmation on pesticide analysis. The LC-MS and LC-MS/MS strategies developed were successfully applied for the analysis and confirmation of pesticides in different types of fruit and vegetables samples, and examples of the screening, quantitation and confirmation of pesticides in these samples are shown in this work.

Cover -- Half Title -- Title Page -- Copyright Page -- Preface -- Acknowledgments -- Table of Contents -- Introduction -- Extracted Ion Chromatography -- Ignitable Liquid Classification -- Brand/Product Identification -- Data Collection -- Sample Preparation -- Data Presentation -- How to Use this Book -- Classification Flowchart -- Data -- Hydrocarbons and Aromatics Standards -- Distillates -- Gasolines -- Oxygenated Solvents -- Isoparaffinic Products -- Normal Alkane Products -- Aromatic Solvents -- Naphthenic Paraffinic Products -- Mixtures and Miscellaneous Products -- Appendices -- Appendix A: Computer Program for HP Chemstation -- Appendix B: Hydrocarbon Range Index -- Appendix C: Distillate Index -- Appendix D: Oxygenate Index -- Appendix E: Mixture/Miscellaneous Product Index -- Index.

Department of Chemistry, Ravishankar University, Raipnr-492 010 Department of Chemistry, Government Autonomous Science College, Raipur Manuscript received 4 April 1990, revised 5 December' 1990, accepted 31 May 1991 Chemically pretreated (NaOH, KOH) silica gel samples of surface phase pH 7 0-11.0 were prepared and parameters like surface area, Na and K ion-content and H+ ion-exchange capacity determined. The samples were employed for the sorption desorption study of the amino acids glycine and serine from 90% ethanol solutions The sorption was found to depend on pH of the substrate and the alkali used for the pretreatment. The process was fast and almost athermic. Desorption efficacy and retarding influence on adsorption by electrolytes was in the order : Th(NO3)4 >Al(NO2)2>Mg(NO3)2>NaNO2. The distribution coefficients for adsorption and desorption were employed In their column chromatography

Department of Chemistry, Government College of Science, Raipur (M.P.), India Department of Chemistry, Government Girls' College, Raipur (M.P.), India Manuscript received 28 March 1978, revised S6 .July 1978, accepted 1 August 1978 Alumina samples of various surface pH, prepared by treating Brockmann alumina with varying concentration of hydrochloric acid, have been employed as substrate. The samples have been used for adsorption-desorption of 2 : 4-dinitrophenol and picric acid from water ; under a variety of conditions of concentration, time, temperature and solvents. The adsorption is found to be pH dependent ; and the favourable range is pH 315-5.5. The greater degree of adsorption in short time-interval (10-30 min), low values of heat of adsorption (-1 to - 5 K cal/mole), and easy desorption have been interpreted by ion-exchange mechanism. The two solutes have been separated by column chromatography.

Low-pressure chromatography is a widely implemented purification technique in the sugar industry. It allows for the separation of complex mixtures with different affinities based on a stationary phase, composed of ion exchange resins, and a mobile phase, which is generally water. Industrially, it is implemented in columns with volumes that can reach several hundred cubic meters. The real-life performance for the purification of 2G sugars and organic acids and the advantage of coupling chromatography and nanofiltration for the production of high purity fructose will be explained further in this article.

Application of software in environmental auditing and quality control (Edward Soo) Solid phase extraction techniques and their importance for environmental monitoring (Dean Rood) Supercritical fluid extraction in environmental analysis (Joseph M. Levy) Validation and quality control of pollutants with atomic absorption spectrometry (Ian Shuttler) Application of ICP/OES techniques in environmental QC (T. C. Dymott) Developments in sampling techniques (Elizabeth A. Woolfenden) QA/QC aspects of using GC/MS for environmental analysis (Ray E. Clement) Ion chromatography in environmental monitoring (Roger C. George) Application of CES in environmental analysis (Saul Parry) QC/QA aspects of using HPLC for environmental analysis (Paul Browne) Advances in flow analysis (Richard J. Berman).

The emergence of novel psychoactive substances is an ongoing challenge for analytical toxicologists. Different analogs are continuously introduced in the market to circumvent legislation and to enhance their pharmacological activity. Although detection of drugs in blood indicates recent exposure and link intoxication to the causative agent, urine is still the most preferred testing matrix in clinical and forensic settings. We developed a method for the simultaneous quantification of 8 piperazines, 4 designer amphetamines and 28 synthetic cathinones and 4 metabolites, in urine by liquid chromatography coupled to high-resolution mass spectrometry (LC-HRMS). Data were acquired in full scan and data dependent MS2 mode. Compounds were quantified by precursor ion exact mass, and confirmed by product ion spectra library matching, taking into account product ions' exact mass and intensities. One-hundred μL urine was subjected to solid phase cation exchange extraction (SOLA SCX). The chromatographic reverse-phase separation was achieved with gradient mobile phase of 0.1% formic acid in water and in acetonitrile in 20 min. The assay was linear from 2.5 or 5 to 500μg/L. Imprecision (n=15) was <15.4%, and accuracy (n=15) 84.2-118.5%. Extraction efficiency was 51.2-111.2%, process efficiency 57.7-104.9% and matrix effect ranged from -41.9 to 238.5% (CV<23.3%, except MDBZP CV<34%). Authentic urine specimens (n=62) were analyzed with the method that provides a comprehensive confirmation for 40 new stimulant drugs with specificity and sensitivity.

This article will review common ion exchange-based softening technologies, describing how the most popular of them, the New Regeneration System (NRS) process, might be a key answer in facing the changes coming in 2017. The process's principles and advantages will be explained, as well as the associated production-regeneration sequence. The combined use of additional technologies can play a critical role as well, and this article will demonstrate how the integration of additional technologies – in this case chromatography – can increase competitiveness.

27 p., figuras, tablas y bibliografía ; Gas chromatography coupled to mass spectrometry in negative chemical ionization mode (GC-(NCI)MS) has been applied to the quantification and reliable identification of polybrominated diphenyl ethers (PBDEs) in animal and vegetable samples from aquaculture activities. Matrices analyzed included fish fillet, fish feed, fish oil and linseed oil, their fat content ranged from 5% to 100%. Solid-phase extraction (SPE) (using Florisil and silica cartridges) and normal-phase high performance liquid chromatography were tested for an efficient clean-up in order to obtain sample extracts free of interfering compounds. Combining sulphuric acid digestion and SPE with Florisil led to the highest efficiency in the elimination of interferences from the extracts. The sample procedure developed, together with the application of GC-(NCI)MS for measurement, led to the satisfactory determination of PBDEs at μg kg −1 levels in complex aquaculture matrices with high lipid content. The use of a short and thin film-thickness fused-silica capillary column allowed to determine the problematic BDE 209 with satisfactory results. Three m/z ions were acquired for each analyte, which ensured a reliable identification of compounds detected in samples. ; The authors acknowledge the financial support of the European Union Project: Sustainable Aquafeeds to Maximise the Health Benefits of Farmed Fish for Consumers (AQUAMAX). Contract number: 016249-2. ; Peer reviewed