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Dunn PJH, Malinovsky D, Achtar E, Clarkson C, Goenaga-Infante H. Systematic comparison of post-column isotope dilution using LC-CO-IRMS with qNMR for amino acid purity determination. Anal Bioanal Chem 2019; 411:7207-7220. [PMID: 31515586 PMCID: PMC6838028 DOI: 10.1007/s00216-019-02116-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2019] [Revised: 08/19/2019] [Accepted: 08/24/2019] [Indexed: 10/29/2022]
Abstract
Determination of the purity of a substance traceable to the International System of Units (SI) is important for the production of reference materials affording traceability in quantitative measurements. Post-column isotope dilution using liquid chromatography-chemical oxidation-isotope ratio mass spectrometry (ID-LC-CO-IRMS) has previously been suggested as a means to determine the purity of organic compounds; however, the lack of an uncertainty budget has prevented assessment of the utility this approach until now. In this work, the previously published ID-LC-CO-IRMS methods have not only been improved by direct gravimetric determination of the mass flow of 13C-labelled spike but also a comprehensive uncertainty budget has been established. This enabled direct comparison of the well-characterised ID-LC-CO-IRMS method to quantitative nuclear magnetic resonance spectroscopy (qNMR) for purity determination using valine as the model compound. The ID-LC-CO-IRMS and qNMR methods provided results that were in agreement within the associated measurement uncertainty for the purity of a sample of valine of (97.1 ± 4.7)% and (99.64 ± 0.20)%, respectively (expanded uncertainties, k = 2). The magnitude of the measurement uncertainty for ID-LC-CO-IRMS determination of valine purity precludes the use of this method for determination of purity by direct analysis of the main component in the majority of situations; however, a mass balance approach is expected to result in significantly improved measurement uncertainty.
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Affiliation(s)
- Philip J H Dunn
- National Measurement Laboratory, LGC Limited, Queen's Road, Teddington, Middlesex, TW11 0LY, UK.
| | - Dmitry Malinovsky
- National Measurement Laboratory, LGC Limited, Queen's Road, Teddington, Middlesex, TW11 0LY, UK
| | - Eli Achtar
- National Measurement Laboratory, LGC Limited, Queen's Road, Teddington, Middlesex, TW11 0LY, UK
| | - Cailean Clarkson
- National Measurement Laboratory, LGC Limited, Queen's Road, Teddington, Middlesex, TW11 0LY, UK
| | - Heidi Goenaga-Infante
- National Measurement Laboratory, LGC Limited, Queen's Road, Teddington, Middlesex, TW11 0LY, UK
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2
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Köster D, Sanchez Villalobos IM, Jochmann MA, Brand WA, Schmidt TC. New Concepts for the Determination of Oxidation Efficiencies in Liquid Chromatography-Isotope Ratio Mass Spectrometry. Anal Chem 2019; 91:5067-5073. [PMID: 30892863 DOI: 10.1021/acs.analchem.8b05315] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
In liquid chromatography coupled to isotope ratio mass spectrometry (LC-IRMS), analytes are separated on an LC system and consecutively oxidized to CO2, which is required for the determination of compound-specific carbon isotope ratios. Oxidation is performed in an online reactor by sulfate radicals. Reaction conditions in the interface depend on the flow conditions determined by the LC method and the flow rates and concentrations of oxidation agent and phosphoric acid added in the interface. To determine accurate isotope ratios, a quantitative conversion of the carbon contained in the analyte to the CO2 measurement gas is a prerequisite. Oxidation efficiencies are not commonly evaluated during method development, although certain analytes are known to be difficult to be oxidized by sulfate radicals. For the assessment of the oxidation efficiency of the LC-IRMS system, three different approaches were evaluated. (1) Residual organic carbon in the eluent stream of the interface was determined to calculate oxidation yields depending on the initial analyte concentration. (2) The IRMS response was calibrated to an inorganic carbon reference material to determine oxidation efficiencies with the help of the IRMS as a detector. (3) The oxidation temperature was deliberately reduced while monitoring the δ13C and signal intensity. The common assumption that a linear relation of IRMS signal to analyte concentration is an indicator for complete oxidation in LC-IRMS could be disproved. All three approaches can be applied for future method development in LC-IRMS, monitoring of existing flow injection applications, as well as for verification of complete oxidation in established LC-IRMS methods.
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Affiliation(s)
| | | | | | - Willi A Brand
- Max Planck Institute for Biogeochemistry , Hans-Knöll-Strasse 10 , 07745 Jena , Germany
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3
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Abstract
Compound-specific isotope analysis encompasses a variety of methods for examining the naturally occurring isotope ratios of individual organic molecules. In marine environments, these methods have revealed heterogeneous sources and alteration processes that underlie the more commonly measured isotope ratios of bulk materials, as well as revealing signatures of marine metabolisms that may otherwise be impossible to isolate. Recently, compound-specific isotopic techniques have improved the reconstruction of metazoan diets and revealed a new potential of metazoan biomass as an archive of paleoecological information. Despite six decades of practice and a diversity of applications, the use of compound-specific isotopic techniques remains uncommon in marine studies. This review examines broad theoretical motivations behind compound-specific isotopic approaches, some applications to studies of marine carbon cycling and trophic relationships, and methodological limitations. In coming years, improvements in analytical efficiency and molecular or intramolecular specificity may transform compound-specific isotope analysis into a tool that can be applied more broadly and help to build global oceanographic data sets.
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Affiliation(s)
- Hilary G Close
- Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, Florida 33149, USA;
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Willach S, Lutze HV, Eckey K, Löppenberg K, Lüling M, Terhalle J, Wolbert JB, Jochmann MA, Karst U, Schmidt TC. Degradation of sulfamethoxazole using ozone and chlorine dioxide - Compound-specific stable isotope analysis, transformation product analysis and mechanistic aspects. WATER RESEARCH 2017; 122:280-289. [PMID: 28609731 DOI: 10.1016/j.watres.2017.06.001] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2017] [Revised: 05/29/2017] [Accepted: 06/01/2017] [Indexed: 06/07/2023]
Abstract
The sulfonamide antibiotic sulfamethoxazole (SMX) is a widely detected micropollutant in surface and groundwaters. Oxidative treatment with e.g. ozone or chlorine dioxide is regularly applied for disinfection purposes at the same time exhibiting a high potential for removal of micropollutants. Especially for nitrogen containing compounds such as SMX, the related reaction mechanisms are largely unknown. In this study, we systematically investigated reaction stoichiometry, product formation and reaction mechanisms in reactions of SMX with ozone and chlorine dioxide. To this end, the neutral and anionic SMX species, which may occur at typical pH-values of water treatment were studied. Two moles of chlorine dioxide and approximately three moles of ozone were consumed per mole SMX degraded. Oxidation of SMX with ozone and chlorine dioxide leads in both cases to six major transformation products (TPs) as revealed by high-resolution mass spectrometry (HRMS). Tentatively formulated TP structures from other studies could partly be confirmed by compound-specific stable isotope analysis (CSIA). However, for one TP, a hydroxylated SMX, it was not possible by HRMS alone to identify whether hydroxylation occurred at the aromatic ring, as suggested in literature before, or at the anilinic nitrogen. By means of CSIA and an analytical standard it was possible to identify sulfamethoxazole hydroxylamine unequivocally as one of the TPs of the reaction of SMX with ozone as well as with chlorine dioxide. H-abstraction and electron transfer at the anilinic nitrogen are suggested as likely initial reactions of ozone and chlorine dioxide, respectively, leading to its formation. Oxidation of anionic SMX with ozone did not show any significant isotopic fractionation whereas the other reactions studied resulted in a significant carbon isotope fractionation.
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Affiliation(s)
- Sarah Willach
- University of Duisburg-Essen, Faculty of Chemistry, Instrumental Analytical Chemistry, Universitaetsstr. 5, D-45141 Essen, Germany
| | - Holger V Lutze
- University of Duisburg-Essen, Faculty of Chemistry, Instrumental Analytical Chemistry, Universitaetsstr. 5, D-45141 Essen, Germany; IWW Water Centre, Moritzstr. 26, D-45476 Muelheim an der Ruhr, Germany; Centre for Water and Environmental Research (ZWU), Universitaetsstr. 5, D-45141 Essen, Germany
| | - Kevin Eckey
- University of Muenster, Institute of Inorganic and Analytical Chemistry, Corrensstr. 30, D-48149 Muenster, Germany
| | - Katja Löppenberg
- University of Duisburg-Essen, Faculty of Chemistry, Instrumental Analytical Chemistry, Universitaetsstr. 5, D-45141 Essen, Germany
| | - Michelle Lüling
- University of Duisburg-Essen, Faculty of Chemistry, Instrumental Analytical Chemistry, Universitaetsstr. 5, D-45141 Essen, Germany
| | - Jens Terhalle
- University of Duisburg-Essen, Faculty of Chemistry, Instrumental Analytical Chemistry, Universitaetsstr. 5, D-45141 Essen, Germany
| | - Jens-Benjamin Wolbert
- University of Duisburg-Essen, Faculty of Chemistry, Instrumental Analytical Chemistry, Universitaetsstr. 5, D-45141 Essen, Germany
| | - Maik A Jochmann
- University of Duisburg-Essen, Faculty of Chemistry, Instrumental Analytical Chemistry, Universitaetsstr. 5, D-45141 Essen, Germany; Centre for Water and Environmental Research (ZWU), Universitaetsstr. 5, D-45141 Essen, Germany
| | - Uwe Karst
- University of Muenster, Institute of Inorganic and Analytical Chemistry, Corrensstr. 30, D-48149 Muenster, Germany
| | - Torsten C Schmidt
- University of Duisburg-Essen, Faculty of Chemistry, Instrumental Analytical Chemistry, Universitaetsstr. 5, D-45141 Essen, Germany; IWW Water Centre, Moritzstr. 26, D-45476 Muelheim an der Ruhr, Germany; Centre for Water and Environmental Research (ZWU), Universitaetsstr. 5, D-45141 Essen, Germany.
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Tea I, Tcherkez G. Natural Isotope Abundance in Metabolites: Techniques and Kinetic Isotope Effect Measurement in Plant, Animal, and Human Tissues. Methods Enzymol 2017; 596:113-147. [PMID: 28911768 DOI: 10.1016/bs.mie.2017.07.020] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The natural isotope abundance in bulk organic matter or tissues is not a sufficient base to investigate physiological properties, biosynthetic mechanisms, and nutrition sources of biological systems. In fact, isotope effects in metabolism lead to a heterogeneous distribution of 2H, 18O, 13C, and 15N isotopes in metabolites. Therefore, compound-specific isotopic analysis (CSIA) is crucial to biological and medical applications of stable isotopes. Here, we review methods to implement CSIA for 15N and 13C from plant, animal, and human samples and discuss technical solutions that have been used for the conversion to CO2 and N2 for IRMS analysis, derivatization and isotope effect measurements. It appears that despite the flexibility of instruments used for CSIA, there is no universal method simply because the chemical nature of metabolites of interest varies considerably. Also, CSIA methods are often limited by isotope effects in sample preparation or the addition of atoms from the derivatizing reagents, and this implies that corrections must be made to calculate a proper δ-value. Therefore, CSIA has an enormous potential for biomedical applications, but its utilization requires precautions for its successful application.
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Affiliation(s)
- Illa Tea
- Research School of Biology, Australian National University, Canberra, ACT, Australia; Cancer Metabolism and Genetics Group, John Curtin School of Medical Research, Australian National University, Canberra, ACT, Australia; EBSI Team, CEISAM, University of Nantes-CNRS UMR 6230, Nantes, France
| | - Guillaume Tcherkez
- Research School of Biology, Australian National University, Canberra, ACT, Australia.
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Federherr E, Kupka HJ, Cerli C, Kalbitz K, Dunsbach R, Loos A, de Reus M, Lange L, Panetta RJ, Schmidt TC. A novel tool for stable nitrogen isotope analysis in aqueous samples. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2016; 30:2537-2544. [PMID: 27619634 DOI: 10.1002/rcm.7740] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Revised: 09/08/2016] [Accepted: 09/09/2016] [Indexed: 06/06/2023]
Abstract
RATIONALE Bulk stable isotope analysis (BSIA) of dissolved matter (e.g. dissolved organic carbon, total nitrogen bound (TNb ), etc.) is of particular importance since this pool is a prime conduit in the cycling of N and C. Studying the two elemental pools is of importance, as transformation and transport processes of N and C are inextricably linked in all biologically mediated systems. No system able to analyze natural abundance stable carbon and nitrogen isotope composition in aqueous samples (without offline sample preparation) and simultaneously has been reported so far. Extension of the high-temperature combustion (HTC) system, to be capable of measuring TNb stable nitrogen isotope composition, is described in this study. METHODS To extend the TOC analyzer to be capable of measuring TNb , modifications from the HTC high-performance liquid chromatography/isotope ratio mass spectrometry (HPLC/IRMS) interface were implemented and expanded. A reduction reactor for conversion of NOx into N2 was implemented into the new developed system. The extension addresses mainly the development of the focusing unit for nitrogen and a degassing device for online separation of TNb from molecular nitrogen (N2 ) prior to injection. RESULTS The proof of principle of the system was demonstrated with different compound solutions. In this initial testing, the δ15 NAIR-N2 values of the tested compounds were determined with precision and trueness of typically ≤0.5‰. Good results (u ≤ 0.5‰) could be achieved down to a TNb concentration of 40 mgN/L and acceptable results (u ≤ 1.0‰) down to 5 mgN/L. In addition, the development resulted in the first system reported to be suitable for simultaneous and direct δ13 C and δ15 N BSIA of aqueous samples. CONCLUSIONS The development resulted in the first system shown to be suitable for both δ13 C and δ15 N direct BSIA in aqueous samples. This system could open up new possibilities in SIA-based research fields. Copyright © 2016 John Wiley & Sons, Ltd.
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Affiliation(s)
- E Federherr
- Research and Innovation, Elementar Analysensysteme GmbH, Donaustr. 7, 63452, Hanau, Germany
- Instrumental Analytical Chemistry, University of Duisburg-Essen, Universitätsstr. 5, 45141, Essen, Germany
| | - H J Kupka
- Research and Innovation, Elementar Analysensysteme GmbH, Donaustr. 7, 63452, Hanau, Germany
| | - C Cerli
- Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Science Park 904, 1098, XH, Amsterdam, The Netherlands
| | - K Kalbitz
- Institute of Soil Science and Site Ecology, Technical University of Dresden, Pienner Str. 21, 01737, Tharandt, Germany
| | - R Dunsbach
- Research and Innovation, Taunus Instruments GmbH, Berlinerstr. 2, 61267, Neu-Anspach, Germany
| | - A Loos
- Research and Innovation, Elementar Analysensysteme GmbH, Donaustr. 7, 63452, Hanau, Germany
| | - M de Reus
- Research and Innovation, Elementar Analysensysteme GmbH, Donaustr. 7, 63452, Hanau, Germany
| | - L Lange
- Research and Innovation, Elementar Analysensysteme GmbH, Donaustr. 7, 63452, Hanau, Germany
| | - R J Panetta
- Research and Innovation, Isoprime Ltd, Cheadle Hulme, SK8 6PT, UK
| | - T C Schmidt
- Instrumental Analytical Chemistry, University of Duisburg-Essen, Universitätsstr. 5, 45141, Essen, Germany
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7
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A reliable compound-specific nitrogen isotope analysis of amino acids by GC-C-IRMS following derivatisation into N -pivaloyl- iso -propyl (NPIP)esters for high-resolution food webs estimation. J Chromatogr B Analyt Technol Biomed Life Sci 2016; 1033-1034:382-389. [DOI: 10.1016/j.jchromb.2016.09.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2016] [Revised: 08/30/2016] [Accepted: 09/02/2016] [Indexed: 11/24/2022]
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8
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Zhang Z, Xiao H, Zheng N, Gao X, Zhu R. Compound-Specific Isotope Analysis of Amino Acid Labeling with Stable Isotope Nitrogen (15N) in Higher Plants. Chromatographia 2016. [DOI: 10.1007/s10337-016-3126-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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