The Experts below are selected from a list of 98973 Experts worldwide ranked by ideXlab platform
Martin Elsner - One of the best experts on this subject based on the ideXlab platform.
-
13c and 15n Isotope Analysis of desphenylchloridazon by liquid chromatography Isotope ratio mass spectrometry and derivatization gas chromatography Isotope ratio mass spectrometry
Analytical Chemistry, 2019Co-Authors: Aileen Melsbach, Thomas B Hofstetter, Violaine Ponsin, Clara Torrento, Christina Lihl, Daniel Hunkeler, Martin ElsnerAbstract:The widespread application of herbicides impacts surface water and groundwater. Metabolites (e.g., desphenylchloridazon from chloridazon) may be persistent and even more polar than the parent herbicide, which increases the risk of groundwater contamination. When parent herbicides are still applied, metabolites are constantly formed and may also be degraded. Evaluating their degradation on the basis of concentration measurements is, therefore, difficult. This study presents compound-specific stable-Isotope Analysis (CSIA) of nitrogen- and carbon-Isotope ratios at natural abundances as an alternative analytical approach to track the origin, formation, and degradation of desphenylchloridazon (DPC), the major degradation product of the herbicide chloridazon. Methods were developed and validated for carbon- and nitrogen-Isotope Analysis (δ13C and δ15N) of DPC by liquid chromatography–Isotope-ratio mass spectrometry (LC-IRMS) and derivatization gas chromatography–IRMS (GC-IRMS), respectively. Injecting standard...
-
13C- and 15N‑Isotope Analysis of Desphenylchloridazon by Liquid Chromatography–Isotope-Ratio Mass Spectrometry and Derivatization Gas Chromatography–Isotope-Ratio Mass Spectrometry
2019Co-Authors: Aileen Melsbach, Thomas B Hofstetter, Violaine Ponsin, Christina Lihl, Daniel Hunkeler, Clara Torrentó, Martin ElsnerAbstract:The widespread application of herbicides impacts surface water and groundwater. Metabolites (e.g., desphenylchloridazon from chloridazon) may be persistent and even more polar than the parent herbicide, which increases the risk of groundwater contamination. When parent herbicides are still applied, metabolites are constantly formed and may also be degraded. Evaluating their degradation on the basis of concentration measurements is, therefore, difficult. This study presents compound-specific stable-Isotope Analysis (CSIA) of nitrogen- and carbon-Isotope ratios at natural abundances as an alternative analytical approach to track the origin, formation, and degradation of desphenylchloridazon (DPC), the major degradation product of the herbicide chloridazon. Methods were developed and validated for carbon- and nitrogen-Isotope Analysis (δ13C and δ15N) of DPC by liquid chromatography–Isotope-ratio mass spectrometry (LC-IRMS) and derivatization gas chromatography–IRMS (GC-IRMS), respectively. Injecting standards directly onto an Atlantis LC-column resulted in reproducible δ13C-Isotope Analysis (standard deviation
-
current challenges in compound specific stable Isotope Analysis of environmental organic contaminants
Analytical and Bioanalytical Chemistry, 2012Co-Authors: Martin Elsner, Thomas B Hofstetter, Daniel Hunkeler, Anat Bernstein, Maik A Jochmann, Torsten C Schmidt, Arndt SchimmelmannAbstract:Compound-specific stable-Isotope Analysis (CSIA) has greatly facilitated assessment of sources and transformation processes of organic pollutants. Multielement Isotope Analysis is one of the most promising applications of CSIA because it even enables distinction of different transformation pathways. This review introduces the essential features of continuous-flow Isotope-ratio mass spectrometry (IRMS) and highlights current challenges in environmental Analysis as exemplified for the Isotopes of nitrogen, hydrogen, chlorine, and oxygen. Strategies and recent advances to enable isotopic measurements of polar contaminants, for example pesticides or pharmaceuticals, are discussed with special emphasis on possible solutions for Analysis of low concentrations of contaminants in environmental matrices. Finally, we discuss different levels of calibration and referencing and point out the urgent need for compound-specific Isotope standards for gas chromatography–Isotope-ratio mass spectrometry (GC–IRMS) of organic pollutants.
-
small and reproducible Isotope effects during methylation with trimethylsulfonium hydroxide tmsh a convenient derivatization method for Isotope Analysis of negatively charged molecules
Analytical Chemistry, 2010Co-Authors: Sandra Reinnicke, Anat Bernstein, Martin ElsnerAbstract:Negatively charged analytes must be derivatized prior to gas chromatography-Isotope ratio mass spectrometry (GC-IRMS), with stringent control of Isotope fractionation. Current methods require offline sample preparation. This study tests for the first time trimethylsulfonium hydroxide (TMSH) as online methylation agent prior to Isotope Analysis, addressing the herbicides bentazone and MCPA. Fully automated derivatization was achieved in a temperature-programmable GC injector, where reactants were injected into a packed liner, solvents were removed by split flow, and subsequent flash heating triggered the derivatization, thereby transferring derivatives onto the chromatographic column. Stoichiometric addition of TMSH resulted in complete conversion giving accurate and reproducible nitrogen Isotope values of bentazone. In contrast, reproducible carbon Isotope Analysis required TMSH in > or = 250-fold excess. Contrary to expectations, delta(13)C values became more negative at smaller TMSH excess. This indicates that elevated methyl group concentrations in the pore space of the injection liner facilitated close-to-equilibrium rather than kinetic Isotope fractionation resulting in reproducible derivatization conditions. delta(13)C results under these conditions compared favorably with liquid chromatography-IRMS: low standard deviations (0.3 per thousand for GC-IRMS, 0.1 per thousand for LC-IRMS) and a comparable offset of 1 per thousand compared to elemental analyzer-IRMS demonstrate that both methods represent expedient ways for online Isotope Analysis of anionic target compounds.
-
intramolecular carbon and nitrogen Isotope Analysis by quantitative dry fragmentation of the phenylurea herbicide isoproturon in a combined injector capillary reactor prior to gc separation
Analytical Chemistry, 2007Co-Authors: Holger Penning And, Martin ElsnerAbstract:Potentially, compound-specific Isotope Analysis may provide unique information on source and fate of pesticides in natural systems. Yet for Isotope Analysis, LC-based methods that are based on the use of organic solvents often cannot be used and GC-based Analysis is frequently not possible due to thermolability of the analyte. A typical example of a compound with such properties is isoproturon (3-(4-isopropylphenyl)-1,1-dimethylurea), belonging to the worldwide extensively used phenylurea herbicides. To make isoproturon accessible to carbon and nitrogen Isotope Analysis, we developed a GC-based method during which isoproturon was quantitatively fragmented to dimethylamine and 4-isopropylphenylisocyanate. Fragmentation occurred only partially in the injector but was mainly achieved on a heated capillary column. The fragments were then chromatographically separated and individually measured by Isotope ratio mass spectrometry. The reliability of the method was tested in hydrolysis experiments with three isot...
Christina Lihl - One of the best experts on this subject based on the ideXlab platform.
-
compound specific chlorine Isotope Analysis of the herbicides atrazine acetochlor and metolachlor
Analytical Chemistry, 2019Co-Authors: Violaine Ponsin, Clara Torrento, Christina LihlAbstract:A gas chromatography–single quadrupole mass spectrometry method was developed and validated for compound-specific chlorine Isotope Analysis (Cl-CSIA) of three chlorinated herbicides, atrazine, acet...
-
toward improved accuracy in chlorine Isotope Analysis synthesis routes for in house standards and characterization via complementary mass spectrometry methods
Analytical Chemistry, 2019Co-Authors: Christina Lihl, Aileen Melsbach, Benjamin Heckel, Julian Renpenning, Steffen Kummel, Faina Gelman, Heide K V Schurner, Martina Daubmeier, Anat Bernstein, Orfan ShouakarstashAbstract:Increasing applications of compound-specific chlorine Isotope Analysis (CSIA) emphasize the need for chlorine Isotope standards that bracket a wider range of Isotope values in order to ensure accur...
-
13c and 15n Isotope Analysis of desphenylchloridazon by liquid chromatography Isotope ratio mass spectrometry and derivatization gas chromatography Isotope ratio mass spectrometry
Analytical Chemistry, 2019Co-Authors: Aileen Melsbach, Thomas B Hofstetter, Violaine Ponsin, Clara Torrento, Christina Lihl, Daniel Hunkeler, Martin ElsnerAbstract:The widespread application of herbicides impacts surface water and groundwater. Metabolites (e.g., desphenylchloridazon from chloridazon) may be persistent and even more polar than the parent herbicide, which increases the risk of groundwater contamination. When parent herbicides are still applied, metabolites are constantly formed and may also be degraded. Evaluating their degradation on the basis of concentration measurements is, therefore, difficult. This study presents compound-specific stable-Isotope Analysis (CSIA) of nitrogen- and carbon-Isotope ratios at natural abundances as an alternative analytical approach to track the origin, formation, and degradation of desphenylchloridazon (DPC), the major degradation product of the herbicide chloridazon. Methods were developed and validated for carbon- and nitrogen-Isotope Analysis (δ13C and δ15N) of DPC by liquid chromatography–Isotope-ratio mass spectrometry (LC-IRMS) and derivatization gas chromatography–IRMS (GC-IRMS), respectively. Injecting standard...
-
13C- and 15N‑Isotope Analysis of Desphenylchloridazon by Liquid Chromatography–Isotope-Ratio Mass Spectrometry and Derivatization Gas Chromatography–Isotope-Ratio Mass Spectrometry
2019Co-Authors: Aileen Melsbach, Thomas B Hofstetter, Violaine Ponsin, Christina Lihl, Daniel Hunkeler, Clara Torrentó, Martin ElsnerAbstract:The widespread application of herbicides impacts surface water and groundwater. Metabolites (e.g., desphenylchloridazon from chloridazon) may be persistent and even more polar than the parent herbicide, which increases the risk of groundwater contamination. When parent herbicides are still applied, metabolites are constantly formed and may also be degraded. Evaluating their degradation on the basis of concentration measurements is, therefore, difficult. This study presents compound-specific stable-Isotope Analysis (CSIA) of nitrogen- and carbon-Isotope ratios at natural abundances as an alternative analytical approach to track the origin, formation, and degradation of desphenylchloridazon (DPC), the major degradation product of the herbicide chloridazon. Methods were developed and validated for carbon- and nitrogen-Isotope Analysis (δ13C and δ15N) of DPC by liquid chromatography–Isotope-ratio mass spectrometry (LC-IRMS) and derivatization gas chromatography–IRMS (GC-IRMS), respectively. Injecting standards directly onto an Atlantis LC-column resulted in reproducible δ13C-Isotope Analysis (standard deviation
Julian Renpenning - One of the best experts on this subject based on the ideXlab platform.
-
requirements for chromium reactors for use in the determination of h Isotopes in compound specific stable Isotope Analysis of chlorinated compounds
Analytical Chemistry, 2020Co-Authors: Tetyana Gilevska, Julian Renpenning, Steffen Kummel, Matthias Gehre, Ann Sullivan Ojeda, Ivonne Nijenhuis, Barbara Sherwood LollarAbstract:There is a strong need for careful quality control in hydrogen compound-specific stable Isotope Analysis (CSIA) of halogenated compounds. This arises in part due to the lack of universal design of the chromium (Cr) reactors. In this study, factors that optimize the critical performance parameter, linearity, for the Cr reduction method for hydrogen Isotope Analysis were identified and evaluated. These include the effects of short and long vertically mounted reactors and temperature profiles on trapping of Cl to ensure accurate and precise hydrogen Isotope measurements. This paper demonstrates the critical parameters that need consideration to optimize any Cr reactor applications to ensure the accuracy of δ2H Analysis for organic compounds and to enhance intercomparability for both international standards and reference materials run by continuous flow versus an elemental analyzer.
-
toward improved accuracy in chlorine Isotope Analysis synthesis routes for in house standards and characterization via complementary mass spectrometry methods
Analytical Chemistry, 2019Co-Authors: Christina Lihl, Aileen Melsbach, Benjamin Heckel, Julian Renpenning, Steffen Kummel, Faina Gelman, Heide K V Schurner, Martina Daubmeier, Anat Bernstein, Orfan ShouakarstashAbstract:Increasing applications of compound-specific chlorine Isotope Analysis (CSIA) emphasize the need for chlorine Isotope standards that bracket a wider range of Isotope values in order to ensure accur...
-
compound specific hydrogen Isotope Analysis of heteroatom bearing compounds via gas chromatography chromium based high temperature conversion cr htc Isotope ratio mass spectrometry
Analytical Chemistry, 2015Co-Authors: Julian Renpenning, Steffen Kummel, Kristina L Hitzfeld, Arndt Schimmelmann, Matthias GehreAbstract:The traditional high-temperature conversion (HTC) approach toward compound-specific stable Isotope Analysis (CSIA) of hydrogen for heteroatom-bearing (i.e., N, Cl, S) compounds has been afflicted by fractionation bias due to formation of byproducts HCN, HCl, and H2S. This study presents a chromium-based high-temperature conversion (Cr/HTC) approach for organic compounds containing nitrogen, chlorine, and sulfur. Following peak separation along a gas chromatographic (GC) column, the use of thermally stable ceramic Cr/HTC reactors at 1100–1500 °C and chemical sequestration of N, Cl, and S by chromium result in quantitative conversion of compound-specific organic hydrogen to H2 analyte gas. The overall hydrogen Isotope Analysis via GC–Cr/HTC–Isotope ratio mass spectrometry (IRMS) achieved a precision of better than ± 5 mUr along the VSMOW-SLAP scale. The accuracy of GC–Cr/HTC–IRMS was validated with organic reference materials (RM) in comparison with online EA–Cr/HTC–IRMS and offline dual-inlet IRMS. The uti...
-
development and validation of an universal interface for compound specific stable Isotope Analysis of chlorine 37cl 35cl by gc high temperature conversion htc ms irms
Analytical Chemistry, 2015Co-Authors: Julian Renpenning, Tetyana Gilevska, Kristina L Hitzfeld, Matthias Gehre, Hanshermann RichnowAbstract:A universal application of compound-specific Isotope Analysis of chlorine was thus far limited by the availability of suitable Analysis techniques. In this study, gas chromatography in combination with a high-temperature conversion interface (GC-HTC), converting organic chlorine in the presence of H2 to gaseous HCl, was coupled to a dual-detection system, combining an ion trap mass spectrometer (MS) and Isotope-ratio mass spectrometer (IRMS). The combination of the MS/IRMS detection enabled a detailed characterization, optimization, and online monitoring of the high-temperature conversion process via ion trap MS as well as a simultaneous chlorine Isotope Analysis by the IRMS. Using GC-HTC-MS/IRMS, chlorine Isotope Analysis at optimized conversion conditions resulted in very accurate Isotope values (δ37ClSMOC) for measured reference material with known Isotope composition, including chlorinated ethylene, chloromethane, hexachlorocyclohexane, and trichloroacetic acids methyl ester. Respective detection limi...
Violaine Ponsin - One of the best experts on this subject based on the ideXlab platform.
-
compound specific chlorine Isotope Analysis of the herbicides atrazine acetochlor and metolachlor
Analytical Chemistry, 2019Co-Authors: Violaine Ponsin, Clara Torrento, Christina LihlAbstract:A gas chromatography–single quadrupole mass spectrometry method was developed and validated for compound-specific chlorine Isotope Analysis (Cl-CSIA) of three chlorinated herbicides, atrazine, acet...
-
13c and 15n Isotope Analysis of desphenylchloridazon by liquid chromatography Isotope ratio mass spectrometry and derivatization gas chromatography Isotope ratio mass spectrometry
Analytical Chemistry, 2019Co-Authors: Aileen Melsbach, Thomas B Hofstetter, Violaine Ponsin, Clara Torrento, Christina Lihl, Daniel Hunkeler, Martin ElsnerAbstract:The widespread application of herbicides impacts surface water and groundwater. Metabolites (e.g., desphenylchloridazon from chloridazon) may be persistent and even more polar than the parent herbicide, which increases the risk of groundwater contamination. When parent herbicides are still applied, metabolites are constantly formed and may also be degraded. Evaluating their degradation on the basis of concentration measurements is, therefore, difficult. This study presents compound-specific stable-Isotope Analysis (CSIA) of nitrogen- and carbon-Isotope ratios at natural abundances as an alternative analytical approach to track the origin, formation, and degradation of desphenylchloridazon (DPC), the major degradation product of the herbicide chloridazon. Methods were developed and validated for carbon- and nitrogen-Isotope Analysis (δ13C and δ15N) of DPC by liquid chromatography–Isotope-ratio mass spectrometry (LC-IRMS) and derivatization gas chromatography–IRMS (GC-IRMS), respectively. Injecting standard...
-
13C- and 15N‑Isotope Analysis of Desphenylchloridazon by Liquid Chromatography–Isotope-Ratio Mass Spectrometry and Derivatization Gas Chromatography–Isotope-Ratio Mass Spectrometry
2019Co-Authors: Aileen Melsbach, Thomas B Hofstetter, Violaine Ponsin, Christina Lihl, Daniel Hunkeler, Clara Torrentó, Martin ElsnerAbstract:The widespread application of herbicides impacts surface water and groundwater. Metabolites (e.g., desphenylchloridazon from chloridazon) may be persistent and even more polar than the parent herbicide, which increases the risk of groundwater contamination. When parent herbicides are still applied, metabolites are constantly formed and may also be degraded. Evaluating their degradation on the basis of concentration measurements is, therefore, difficult. This study presents compound-specific stable-Isotope Analysis (CSIA) of nitrogen- and carbon-Isotope ratios at natural abundances as an alternative analytical approach to track the origin, formation, and degradation of desphenylchloridazon (DPC), the major degradation product of the herbicide chloridazon. Methods were developed and validated for carbon- and nitrogen-Isotope Analysis (δ13C and δ15N) of DPC by liquid chromatography–Isotope-ratio mass spectrometry (LC-IRMS) and derivatization gas chromatography–IRMS (GC-IRMS), respectively. Injecting standards directly onto an Atlantis LC-column resulted in reproducible δ13C-Isotope Analysis (standard deviation
Aileen Melsbach - One of the best experts on this subject based on the ideXlab platform.
-
toward improved accuracy in chlorine Isotope Analysis synthesis routes for in house standards and characterization via complementary mass spectrometry methods
Analytical Chemistry, 2019Co-Authors: Christina Lihl, Aileen Melsbach, Benjamin Heckel, Julian Renpenning, Steffen Kummel, Faina Gelman, Heide K V Schurner, Martina Daubmeier, Anat Bernstein, Orfan ShouakarstashAbstract:Increasing applications of compound-specific chlorine Isotope Analysis (CSIA) emphasize the need for chlorine Isotope standards that bracket a wider range of Isotope values in order to ensure accur...
-
13c and 15n Isotope Analysis of desphenylchloridazon by liquid chromatography Isotope ratio mass spectrometry and derivatization gas chromatography Isotope ratio mass spectrometry
Analytical Chemistry, 2019Co-Authors: Aileen Melsbach, Thomas B Hofstetter, Violaine Ponsin, Clara Torrento, Christina Lihl, Daniel Hunkeler, Martin ElsnerAbstract:The widespread application of herbicides impacts surface water and groundwater. Metabolites (e.g., desphenylchloridazon from chloridazon) may be persistent and even more polar than the parent herbicide, which increases the risk of groundwater contamination. When parent herbicides are still applied, metabolites are constantly formed and may also be degraded. Evaluating their degradation on the basis of concentration measurements is, therefore, difficult. This study presents compound-specific stable-Isotope Analysis (CSIA) of nitrogen- and carbon-Isotope ratios at natural abundances as an alternative analytical approach to track the origin, formation, and degradation of desphenylchloridazon (DPC), the major degradation product of the herbicide chloridazon. Methods were developed and validated for carbon- and nitrogen-Isotope Analysis (δ13C and δ15N) of DPC by liquid chromatography–Isotope-ratio mass spectrometry (LC-IRMS) and derivatization gas chromatography–IRMS (GC-IRMS), respectively. Injecting standard...
-
13C- and 15N‑Isotope Analysis of Desphenylchloridazon by Liquid Chromatography–Isotope-Ratio Mass Spectrometry and Derivatization Gas Chromatography–Isotope-Ratio Mass Spectrometry
2019Co-Authors: Aileen Melsbach, Thomas B Hofstetter, Violaine Ponsin, Christina Lihl, Daniel Hunkeler, Clara Torrentó, Martin ElsnerAbstract:The widespread application of herbicides impacts surface water and groundwater. Metabolites (e.g., desphenylchloridazon from chloridazon) may be persistent and even more polar than the parent herbicide, which increases the risk of groundwater contamination. When parent herbicides are still applied, metabolites are constantly formed and may also be degraded. Evaluating their degradation on the basis of concentration measurements is, therefore, difficult. This study presents compound-specific stable-Isotope Analysis (CSIA) of nitrogen- and carbon-Isotope ratios at natural abundances as an alternative analytical approach to track the origin, formation, and degradation of desphenylchloridazon (DPC), the major degradation product of the herbicide chloridazon. Methods were developed and validated for carbon- and nitrogen-Isotope Analysis (δ13C and δ15N) of DPC by liquid chromatography–Isotope-ratio mass spectrometry (LC-IRMS) and derivatization gas chromatography–IRMS (GC-IRMS), respectively. Injecting standards directly onto an Atlantis LC-column resulted in reproducible δ13C-Isotope Analysis (standard deviation