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Henricus T S Boschker - One of the best experts on this subject based on the ideXlab platform.

  • comparison of gas chromatography isotope ratio Mass Spectrometry and liquid chromatography isotope ratio Mass Spectrometry for carbon stable isotope analysis of carbohydrates
    Rapid Communications in Mass Spectrometry, 2015
    Co-Authors: Tanja C W Moerdijkpoortvliet, Henk Schierbeek, Marco Houtekamer, Tom Van Engeland, Delphine Derrien, Lucas J Stal, Henricus T S Boschker
    Abstract:

    Rationale: We compared gas chromatography/isotope ratio Mass Spectrometry (GC/IRMS) and liquid chromatography/isotope ratio Mass Spectrometry (LC/IRMS) for the measurement of δ13C values in carbohydrates. Contrary to GC/IRMS, no derivatisation is needed for LC/IRMS analysis of carbohydrates. Hence, although LC/IRMS is expected to be more accurate and precise, no direct comparison has been reported. Methods: GC/IRMS with the aldonitrile penta-acetate (ANPA) derivatisation method was compared with LC/IRMS without derivatisation. A large number of glucose standards and a variety of natural samples were analysed for five neutral carbohydrates at natural abundance as well as at 13C-enriched levels. Gas chromatography/chemical ionisation Mass Spectrometry (GC/CIMS) was applied to check for incomplete derivatisation of the carbohydrate, which would impair the accuracy of the GC/IRMS method. Results: The LC/IRMS technique provided excellent precision (±0.08 ‰ and ±3.1 ‰ at natural abundance and enrichment levels, respectively) for the glucose standards and this technique proved to be superior to GC/IRMS (±0.62 ‰ and ±19.8 ‰ at natural abundance and enrichment levels, respectively). For GC/IRMS measurements the derivatisation correction and the conversion of carbohydrates into CO2 had a considerable effect on the measured δ13C values. However, we did not find any significant differences in the accuracy of the two techniques over the full range of natural δ13C abundances and 13C-labelled glucose. The difference in the performance of GC/IRMS and LC/IRMS diminished when the δ13C values were measured in natural samples, because the chromatographic performance and background correction became critical factors, particularly for LC/IRMS. The derivatisation of carbohydrates for the GC/IRMS method was complete. Conclusions: Although both LC/IRMS and GC/IRMS are reliable techniques for compound-specific stable carbon isotope analysis of carbohydrates (provided that derivatisation is complete and the calibration requirements are met), LC/IRMS is the technique of choice. The reasons for this are the improved precision, simpler sample preparation, and straightforward isotopic calibration.

  • Comparison of gas chromatography/isotope ratio Mass Spectrometry and liquid chromatography/isotope ratio Mass Spectrometry for carbon stable-isotope analysis of carbohydrates
    Rapid communications in mass spectrometry : RCM, 2015
    Co-Authors: Tanja C. W. Moerdijk-poortvliet, Henk Schierbeek, Marco Houtekamer, Delphine Derrien, Lucas J Stal, Tom Van Engeland, Henricus T S Boschker
    Abstract:

    Rationale: We compared gas chromatography/isotope ratio Mass Spectrometry (GC/IRMS) and liquid chromatography/isotope ratio Mass Spectrometry (LC/IRMS) for the measurement of δ13C values in carbohydrates. Contrary to GC/IRMS, no derivatisation is needed for LC/IRMS analysis of carbohydrates. Hence, although LC/IRMS is expected to be more accurate and precise, no direct comparison has been reported. Methods: GC/IRMS with the aldonitrile penta-acetate (ANPA) derivatisation method was compared with LC/IRMS without derivatisation. A large number of glucose standards and a variety of natural samples were analysed for five neutral carbohydrates at natural abundance as well as at 13C-enriched levels. Gas chromatography/chemical ionisation Mass Spectrometry (GC/CIMS) was applied to check for incomplete derivatisation of the carbohydrate, which would impair the accuracy of the GC/IRMS method. Results: The LC/IRMS technique provided excellent precision (±0.08 ‰ and ±3.1 ‰ at natural abundance and enrichment levels, respectively) for the glucose standards and this technique proved to be superior to GC/IRMS (±0.62 ‰ and ±19.8 ‰ at natural abundance and enrichment levels, respectively). For GC/IRMS measurements the derivatisation correction and the conversion of carbohydrates into CO2 had a considerable effect on the measured δ13C values. However, we did not find any significant differences in the accuracy of the two techniques over the full range of natural δ13C abundances and 13C-labelled glucose. The difference in the performance of GC/IRMS and LC/IRMS diminished when the δ13C values were measured in natural samples, because the chromatographic performance and background correction became critical factors, particularly for LC/IRMS. The derivatisation of carbohydrates for the GC/IRMS method was complete. Conclusions: Although both LC/IRMS and GC/IRMS are reliable techniques for compound-specific stable carbon isotope analysis of carbohydrates (provided that derivatisation is complete and the calibration requirements are met), LC/IRMS is the technique of choice. The reasons for this are the improved precision, simpler sample preparation, and straightforward isotopic calibration.

  • Comparison of gas chromatography/isotope ratio Mass Spectrometry and liquid chromatography/isotope ratio Mass Spectrometry for carbon stable-isotope analysis of carbohydrates
    Rapid Communications in Mass Spectrometry, 2015
    Co-Authors: Tanja C. W. Moerdijk-poortvliet, Henk Schierbeek, Marco Houtekamer, Delphine Derrien, Lucas J Stal, Tom Van Engeland, Henricus T S Boschker
    Abstract:

    RATIONALE: We compared gas chromatography/isotope ratio Mass Spectrometry (GC/IRMS) and liquid chromatography/isotope ratio Mass Spectrometry (LC/IRMS) for the measurement of delta C-13 values in carbohydrates. Contrary to GC/IRMS, no derivatisation is needed for LC/IRMS analysis of carbohydrates. Hence, although LC/IRMS is expected to be more accurate and precise, no direct comparison has been reported. METHODS: GC/IRMS with the aldonitrile penta-acetate (ANPA) derivatisation method was compared with LC/IRMS without derivatisation. A large number of glucose standards and a variety of natural samples were analysed for five neutral carbohydrates at natural abundance as well as at C-13-enriched levels. Gas chromatography/chemical ionisation Mass Spectrometry (GC/CIMS) was applied to check for incomplete derivatisation of the carbohydrate, which would impair the accuracy of the GC/IRMS method. RESULTS: The LC/IRMS technique provided excellent precision (+/- 0.08 parts per thousand and +/- 3.1 parts per thousand at natural abundance and enrichment levels, respectively) for the glucose standards and this technique proved to be superior to GC/IRMS (+/- 0.62 parts per thousand and +/- 19.8 parts per thousand at natural abundance and enrichment levels, respectively). For GC/IRMS measurements the derivatisation correction and the conversion of carbohydrates into CO2 had a considerable effect on the measured delta C-13 values. However, we did not find any significant differences in the accuracy of the two techniques over the full range of natural delta C-13 abundances and C-13-labelled glucose. The difference in the performance of GC/IRMS and LC/IRMS diminished when the delta C-13 values were measured in natural samples, because the chromatographic performance and background correction became critical factors, particularly for LC/IRMS. The derivatisation of carbohydrates for the GC/IRMS method was complete. CONCLUSIONS: Although both LC/IRMS and GC/IRMS are reliable techniques for compound-specific stable carbon isotope analysis of carbohydrates (provided that derivatisation is complete and the calibration requirements are met), LC/IRMS is the technique of choice. The reasons for this are the improved precision, simpler sample preparation, and straightforward isotopic calibration.

  • analysis of u 13c6 glucose in human plasma using liquid chromatography isotope ratio Mass Spectrometry compared with two other Mass Spectrometry techniques
    Rapid Communications in Mass Spectrometry, 2009
    Co-Authors: Henk Schierbeek, Tanja C W Moerdijkpoortvliet, Henricus T S Boschker, Chris H P Van Den Akker, Frans Te W J Braake, Johannes B Van Goudoever
    Abstract:

    The use of stable isotope labelled glucose provides insight into glucose metabolism. The 13C-isotopic enrichment of glucose is usually measured by gas chromatography/Mass Spectrometry (GC/MS) or gas chromatography/combustion/isotope ratio Mass Spectrometry (GC/C/IRMS). However, in both techniques the samples must be derivatized prior to analysis, which makes sample preparation more labour-intensive and increases the uncertainty of the measured isotopic composition. A novel method for the determination of isotopic enrichment of glucose in human plasma using liquid chromatography/isotope ratio Mass Spectrometry (LC/IRMS) has been developed. Using this technique, for which hardly any sample preparation is needed, we showed that both the enrichment and the concentration could be measured with very high precision using only 20 µL of plasma. In addition, a comparison with GC/MS and GC/IRMS showed that the best performance was achieved with the LC/IRMS method making it the method of choice for the measurement of 13C-isotopic enrichment in plasma samples. Copyright © 2009 John Wiley & Sons, Ltd.

  • Analysis of [U-13C6]glucose in human plasma using liquid chromatography/isotope ratio Mass Spectrometry compared with two other Mass Spectrometry techniques.
    Rapid communications in mass spectrometry : RCM, 2009
    Co-Authors: Henk Schierbeek, Henricus T S Boschker, Tanja C. W. Moerdijk-poortvliet, Frans Te W J Braake, Chris H. P. Van Den Akker, Johannes B. Van Goudoever
    Abstract:

    The use of stable isotope labelled glucose provides insight into glucose metabolism. The 13C-isotopic enrichment of glucose is usually measured by gas chromatography/Mass Spectrometry (GC/MS) or gas chromatography/combustion/isotope ratio Mass Spectrometry (GC/C/IRMS). However, in both techniques the samples must be derivatized prior to analysis, which makes sample preparation more labour-intensive and increases the uncertainty of the measured isotopic composition. A novel method for the determination of isotopic enrichment of glucose in human plasma using liquid chromatography/isotope ratio Mass Spectrometry (LC/IRMS) has been developed. Using this technique, for which hardly any sample preparation is needed, we showed that both the enrichment and the concentration could be measured with very high precision using only 20 µL of plasma. In addition, a comparison with GC/MS and GC/IRMS showed that the best performance was achieved with the LC/IRMS method making it the method of choice for the measurement of 13C-isotopic enrichment in plasma samples. Copyright © 2009 John Wiley & Sons, Ltd.

Henk Schierbeek - One of the best experts on this subject based on the ideXlab platform.

  • comparison of gas chromatography isotope ratio Mass Spectrometry and liquid chromatography isotope ratio Mass Spectrometry for carbon stable isotope analysis of carbohydrates
    Rapid Communications in Mass Spectrometry, 2015
    Co-Authors: Tanja C W Moerdijkpoortvliet, Henk Schierbeek, Marco Houtekamer, Tom Van Engeland, Delphine Derrien, Lucas J Stal, Henricus T S Boschker
    Abstract:

    Rationale: We compared gas chromatography/isotope ratio Mass Spectrometry (GC/IRMS) and liquid chromatography/isotope ratio Mass Spectrometry (LC/IRMS) for the measurement of δ13C values in carbohydrates. Contrary to GC/IRMS, no derivatisation is needed for LC/IRMS analysis of carbohydrates. Hence, although LC/IRMS is expected to be more accurate and precise, no direct comparison has been reported. Methods: GC/IRMS with the aldonitrile penta-acetate (ANPA) derivatisation method was compared with LC/IRMS without derivatisation. A large number of glucose standards and a variety of natural samples were analysed for five neutral carbohydrates at natural abundance as well as at 13C-enriched levels. Gas chromatography/chemical ionisation Mass Spectrometry (GC/CIMS) was applied to check for incomplete derivatisation of the carbohydrate, which would impair the accuracy of the GC/IRMS method. Results: The LC/IRMS technique provided excellent precision (±0.08 ‰ and ±3.1 ‰ at natural abundance and enrichment levels, respectively) for the glucose standards and this technique proved to be superior to GC/IRMS (±0.62 ‰ and ±19.8 ‰ at natural abundance and enrichment levels, respectively). For GC/IRMS measurements the derivatisation correction and the conversion of carbohydrates into CO2 had a considerable effect on the measured δ13C values. However, we did not find any significant differences in the accuracy of the two techniques over the full range of natural δ13C abundances and 13C-labelled glucose. The difference in the performance of GC/IRMS and LC/IRMS diminished when the δ13C values were measured in natural samples, because the chromatographic performance and background correction became critical factors, particularly for LC/IRMS. The derivatisation of carbohydrates for the GC/IRMS method was complete. Conclusions: Although both LC/IRMS and GC/IRMS are reliable techniques for compound-specific stable carbon isotope analysis of carbohydrates (provided that derivatisation is complete and the calibration requirements are met), LC/IRMS is the technique of choice. The reasons for this are the improved precision, simpler sample preparation, and straightforward isotopic calibration.

  • Comparison of gas chromatography/isotope ratio Mass Spectrometry and liquid chromatography/isotope ratio Mass Spectrometry for carbon stable-isotope analysis of carbohydrates
    Rapid communications in mass spectrometry : RCM, 2015
    Co-Authors: Tanja C. W. Moerdijk-poortvliet, Henk Schierbeek, Marco Houtekamer, Delphine Derrien, Lucas J Stal, Tom Van Engeland, Henricus T S Boschker
    Abstract:

    Rationale: We compared gas chromatography/isotope ratio Mass Spectrometry (GC/IRMS) and liquid chromatography/isotope ratio Mass Spectrometry (LC/IRMS) for the measurement of δ13C values in carbohydrates. Contrary to GC/IRMS, no derivatisation is needed for LC/IRMS analysis of carbohydrates. Hence, although LC/IRMS is expected to be more accurate and precise, no direct comparison has been reported. Methods: GC/IRMS with the aldonitrile penta-acetate (ANPA) derivatisation method was compared with LC/IRMS without derivatisation. A large number of glucose standards and a variety of natural samples were analysed for five neutral carbohydrates at natural abundance as well as at 13C-enriched levels. Gas chromatography/chemical ionisation Mass Spectrometry (GC/CIMS) was applied to check for incomplete derivatisation of the carbohydrate, which would impair the accuracy of the GC/IRMS method. Results: The LC/IRMS technique provided excellent precision (±0.08 ‰ and ±3.1 ‰ at natural abundance and enrichment levels, respectively) for the glucose standards and this technique proved to be superior to GC/IRMS (±0.62 ‰ and ±19.8 ‰ at natural abundance and enrichment levels, respectively). For GC/IRMS measurements the derivatisation correction and the conversion of carbohydrates into CO2 had a considerable effect on the measured δ13C values. However, we did not find any significant differences in the accuracy of the two techniques over the full range of natural δ13C abundances and 13C-labelled glucose. The difference in the performance of GC/IRMS and LC/IRMS diminished when the δ13C values were measured in natural samples, because the chromatographic performance and background correction became critical factors, particularly for LC/IRMS. The derivatisation of carbohydrates for the GC/IRMS method was complete. Conclusions: Although both LC/IRMS and GC/IRMS are reliable techniques for compound-specific stable carbon isotope analysis of carbohydrates (provided that derivatisation is complete and the calibration requirements are met), LC/IRMS is the technique of choice. The reasons for this are the improved precision, simpler sample preparation, and straightforward isotopic calibration.

  • Comparison of gas chromatography/isotope ratio Mass Spectrometry and liquid chromatography/isotope ratio Mass Spectrometry for carbon stable-isotope analysis of carbohydrates
    Rapid Communications in Mass Spectrometry, 2015
    Co-Authors: Tanja C. W. Moerdijk-poortvliet, Henk Schierbeek, Marco Houtekamer, Delphine Derrien, Lucas J Stal, Tom Van Engeland, Henricus T S Boschker
    Abstract:

    RATIONALE: We compared gas chromatography/isotope ratio Mass Spectrometry (GC/IRMS) and liquid chromatography/isotope ratio Mass Spectrometry (LC/IRMS) for the measurement of delta C-13 values in carbohydrates. Contrary to GC/IRMS, no derivatisation is needed for LC/IRMS analysis of carbohydrates. Hence, although LC/IRMS is expected to be more accurate and precise, no direct comparison has been reported. METHODS: GC/IRMS with the aldonitrile penta-acetate (ANPA) derivatisation method was compared with LC/IRMS without derivatisation. A large number of glucose standards and a variety of natural samples were analysed for five neutral carbohydrates at natural abundance as well as at C-13-enriched levels. Gas chromatography/chemical ionisation Mass Spectrometry (GC/CIMS) was applied to check for incomplete derivatisation of the carbohydrate, which would impair the accuracy of the GC/IRMS method. RESULTS: The LC/IRMS technique provided excellent precision (+/- 0.08 parts per thousand and +/- 3.1 parts per thousand at natural abundance and enrichment levels, respectively) for the glucose standards and this technique proved to be superior to GC/IRMS (+/- 0.62 parts per thousand and +/- 19.8 parts per thousand at natural abundance and enrichment levels, respectively). For GC/IRMS measurements the derivatisation correction and the conversion of carbohydrates into CO2 had a considerable effect on the measured delta C-13 values. However, we did not find any significant differences in the accuracy of the two techniques over the full range of natural delta C-13 abundances and C-13-labelled glucose. The difference in the performance of GC/IRMS and LC/IRMS diminished when the delta C-13 values were measured in natural samples, because the chromatographic performance and background correction became critical factors, particularly for LC/IRMS. The derivatisation of carbohydrates for the GC/IRMS method was complete. CONCLUSIONS: Although both LC/IRMS and GC/IRMS are reliable techniques for compound-specific stable carbon isotope analysis of carbohydrates (provided that derivatisation is complete and the calibration requirements are met), LC/IRMS is the technique of choice. The reasons for this are the improved precision, simpler sample preparation, and straightforward isotopic calibration.

  • analysis of u 13c6 glucose in human plasma using liquid chromatography isotope ratio Mass Spectrometry compared with two other Mass Spectrometry techniques
    Rapid Communications in Mass Spectrometry, 2009
    Co-Authors: Henk Schierbeek, Tanja C W Moerdijkpoortvliet, Henricus T S Boschker, Chris H P Van Den Akker, Frans Te W J Braake, Johannes B Van Goudoever
    Abstract:

    The use of stable isotope labelled glucose provides insight into glucose metabolism. The 13C-isotopic enrichment of glucose is usually measured by gas chromatography/Mass Spectrometry (GC/MS) or gas chromatography/combustion/isotope ratio Mass Spectrometry (GC/C/IRMS). However, in both techniques the samples must be derivatized prior to analysis, which makes sample preparation more labour-intensive and increases the uncertainty of the measured isotopic composition. A novel method for the determination of isotopic enrichment of glucose in human plasma using liquid chromatography/isotope ratio Mass Spectrometry (LC/IRMS) has been developed. Using this technique, for which hardly any sample preparation is needed, we showed that both the enrichment and the concentration could be measured with very high precision using only 20 µL of plasma. In addition, a comparison with GC/MS and GC/IRMS showed that the best performance was achieved with the LC/IRMS method making it the method of choice for the measurement of 13C-isotopic enrichment in plasma samples. Copyright © 2009 John Wiley & Sons, Ltd.

  • Analysis of [U-13C6]glucose in human plasma using liquid chromatography/isotope ratio Mass Spectrometry compared with two other Mass Spectrometry techniques.
    Rapid communications in mass spectrometry : RCM, 2009
    Co-Authors: Henk Schierbeek, Henricus T S Boschker, Tanja C. W. Moerdijk-poortvliet, Frans Te W J Braake, Chris H. P. Van Den Akker, Johannes B. Van Goudoever
    Abstract:

    The use of stable isotope labelled glucose provides insight into glucose metabolism. The 13C-isotopic enrichment of glucose is usually measured by gas chromatography/Mass Spectrometry (GC/MS) or gas chromatography/combustion/isotope ratio Mass Spectrometry (GC/C/IRMS). However, in both techniques the samples must be derivatized prior to analysis, which makes sample preparation more labour-intensive and increases the uncertainty of the measured isotopic composition. A novel method for the determination of isotopic enrichment of glucose in human plasma using liquid chromatography/isotope ratio Mass Spectrometry (LC/IRMS) has been developed. Using this technique, for which hardly any sample preparation is needed, we showed that both the enrichment and the concentration could be measured with very high precision using only 20 µL of plasma. In addition, a comparison with GC/MS and GC/IRMS showed that the best performance was achieved with the LC/IRMS method making it the method of choice for the measurement of 13C-isotopic enrichment in plasma samples. Copyright © 2009 John Wiley & Sons, Ltd.

James S. O. Mccullagh - One of the best experts on this subject based on the ideXlab platform.

  • Liquid chromatography/isotope ratio Mass Spectrometry measurement of δ13C of amino acids in plant proteins.
    Rapid communications in mass spectrometry : RCM, 2011
    Co-Authors: Anthony H. Lynch, James S. O. Mccullagh, Robert E. M. Hedges
    Abstract:

    In archaeological studies, the isotopic enrichment values of carbon and nitrogen in bone collagen give a degree of information on dietary composition. The isotopic enrichments of individual amino acids from bone collagen and dietary protein have the potential to provide more precise information about the components of diet. A limited amount of work has been done on this, although the reliability of these studies is potentially limited by fractionation arising through hydrolysis of whole plant tissue (where reaction between amino acids and carbohydrates may occur) and, for certain amino acids, the use of derivatives (particularly trifluoroacetyl derivatives) for gas chromatography/isotope ratio Mass Spectrometry (GC/IRMS) analysis. The present study takes the approach of extracting the protein components of plant tissues before hydrolysis and using liquid chromatography/isotope ratio Mass Spectrometry (LC/IRMS), which does not require derivatisation, for measurement of the isotopic enrichment of the amino acids. The protocol developed offers a methodology for consistent measurement of the δ13C values of amino acids, allowing isotopic differences between the individual amino acids from different plant tissues to be identified. In particular, there are highly significant differences between leaf and seed protein amino acids (leaf minus grain) in the cases of threonine (−4.1‰), aspartic acid (+3.5‰) and serine (−3.2‰). In addition to its intended application in archaeology, the technique will be of value in the fields of plant sciences, nutrition and environmental food-web studies. Copyright © 2011 John Wiley & Sons, Ltd.

  • Review: Current applications and challenges for liquid chromatography coupled to isotope ratio Mass Spectrometry (LC/IRMS)
    Rapid communications in mass spectrometry : RCM, 2011
    Co-Authors: Jean-philippe Godin, James S. O. Mccullagh
    Abstract:

    High-precision isotope analysis is recognized as an essential research tool in many fields of study. Until recently, continuous flow isotope ratio Mass Spectrometry (CF-IRMS) was available via an elemental analyzer or a gas chromatography inlet system for compound-specific analysis of light stable isotopes. In 2004, however, an interface that coupled liquid chromatography with IRMS (LC/IRMS) became commercially available for the first time. This brought the capability for new areas of application, in particular enabling compound-specific δ(13)C analysis of non-volatile, aqueous soluble, compounds from complex mixtures. The interface design brought with it several analytical constraints, however, in particular a lack of compatibility with certain types of chromatography as well as limited flow rates and mobile phase compositions. Routine LC/IRMS methods have, however, been established for measuring the δ(13)C isotopic ratios of underivatized individual compounds for application in archeology, nutrition and physiology, geochemistry, hydrology, soil science and food authenticity. Seven years after its introduction, we review the technical advances and constraints, methodological developments and new applications of liquid chromatography coupled to isotope ratio Mass Spectrometry.

  • Mixed-mode chromatography/isotope ratio Mass Spectrometry.
    Rapid communications in mass spectrometry : RCM, 2010
    Co-Authors: James S. O. Mccullagh
    Abstract:

    Liquid chromatography coupled to molecular Mass Spectrometry (LC/MS) has been a standard technique since the early 1970s but liquid chromatography coupled to high-precision isotope ratio Mass Spectrometry (LC/IRMS) has only been available commercially since 2004. This development has, for the first time, enabled natural abundance and low enrichment delta(13)C measurements to be applied to individual analytes in aqueous mixtures creating new opportunities for IRMS applications, particularly for the isotopic study of biological molecules. A growing number of applications have been published in a range of areas including amino acid metabolism, carbohydrates studies, quantification of cellular and plasma metabolites, dietary tracer and nucleic acid studies. There is strong potential to extend these to new compounds and complex matrices but several challenges face the development of LC/IRMS methods. To achieve accurate isotopic measurements, HPLC separations must provide baseline-resolution between analyte peaks; however, the design of current liquid interfaces places severe restrictions on compatible flow rates and in particular mobile phase compositions. These create a significant challenge on which reports associated with LC/IRMS have not previously focused. Accordingly, this paper will address aspects of chromatography in the context of LC/IRMS, in particular focusing on mixed-mode separations and their benefits in light of these restrictions. It aims to provide an overview of mixed-mode stationary phases and of ways to improve high aqueous separations through manipulation of parameters such as column length, temperature and mobile phase pH. The results of several practical experiments are given using proteogenic amino acids and nucleosides both of which are of noted importance in the LC/IRMS literature. This communication aims to demonstrate that mixed-mode stationary phases provide a flexible approach given the constraints of LC/IRMS interface design and acts as a practical guide for the development of new chromatographic methods compatible with LC/IRMS applications.

  • analysis of amino acid 13c abundance from human and faunal bone collagen using liquid chromatography isotope ratio Mass Spectrometry
    Rapid Communications in Mass Spectrometry, 2006
    Co-Authors: James S. O. Mccullagh, Dieter Juchelka, R E M Hedges
    Abstract:

    : The scope of compound-specific stable isotope analysis has recently been increased with the development of the LC IsoLink which interfaces high-performance liquid chromatography (HPLC) and isotope ratio Mass Spectrometry (IRMS) to provide online LC/IRMS. This enables isotopic measurement of non-volatile compounds previously not amenable to compound-specific analysis or requiring substantial modification for gas chromatography/combustion/isotope ratio Mass Spectrometry (GC/C/IRMS), which results in reduced precision. Amino acids are an example of such compounds. We present a new chromatographic method for the HPLC separation of underivatized amino acids using an acidic, aqueous mobile phase in conjunction with a mixed-mode stationary phase that can be interfaced with the LC IsoLink for compound-specific delta13C analysis. The method utilizes a reversed-phase Primesep-A column with embedded, ionizable, functional groups providing the capability for ion-exchange and hydrophobic interactions. Baseline separation of 15 amino acids and their carbon isotope values are reported with an average standard deviation of 0.18 per thousand (n = 6). In addition delta13C values of 18 amino acids are determined from modern protein and archaeological bone collagen hydrolysates, demonstrating the potential of this method for compound-specific applications in a number of fields including metabolic, ecological and palaeodietary studies.

  • Analysis of amino acid 13C abundance from human and faunal bone collagen using liquid chromatography/isotope ratio Mass Spectrometry.
    Rapid communications in mass spectrometry : RCM, 2006
    Co-Authors: James S. O. Mccullagh, Dieter Juchelka, Robert E. M. Hedges
    Abstract:

    The scope of compound-specific stable isotope analysis has recently been increased with the development of the LC IsoLink which interfaces high-performance liquid chromatography (HPLC) and isotope ratio Mass Spectrometry (IRMS) to provide online LC/IRMS. This enables isotopic measurement of non-volatile compounds previously not amenable to compound-specific analysis or requiring substantial modification for gas chromatography/combustion/isotope ratio Mass Spectrometry (GC/C/IRMS), which results in reduced precision. Amino acids are an example of such compounds. We present a new chromatographic method for the HPLC separation of underivatized amino acids using an acidic, aqueous mobile phase in conjunction with a mixed-mode stationary phase that can be interfaced with the LC IsoLink for compound-specific delta13C analysis. The method utilizes a reversed-phase Primesep-A column with embedded, ionizable, functional groups providing the capability for ion-exchange and hydrophobic interactions. Baseline separation of 15 amino acids and their carbon isotope values are reported with an average standard deviation of 0.18 per thousand (n = 6). In addition delta13C values of 18 amino acids are determined from modern protein and archaeological bone collagen hydrolysates, demonstrating the potential of this method for compound-specific applications in a number of fields including metabolic, ecological and palaeodietary studies.

Torsten C Schmidt - One of the best experts on this subject based on the ideXlab platform.

  • Carbon isotope ratio analysis of steroids by high-temperature liquid chromatography-isotope ratio Mass Spectrometry.
    Analytical chemistry, 2014
    Co-Authors: Lijun Zhang, Dorothea Kujawinski, J. Benjamin Wolbert, Maik Jochmann, Mario Thevis, Thomas Piper, Steffen Wiese, Thorsten Teutenberg, Torsten C Schmidt
    Abstract:

    Generally, compound-specific isotope analysis of steroids is carried out by gas chromatography combined with isotope ratio Mass Spectrometry. Thus, a derivatization of the steroids prior to the measurement is compulsory, and a correction of the isotopic data is often necessary. To overcome this limitation, we present a new approach of high-temperature liquid chromatography coupled with photodiode array detection and isotope ratio Mass Spectrometry (HT-LC/PDA/IRMS) for the carbon isotope ratio analysis of unconjugated steroids. A steroid mixture containing 19-norandrosterone, testosterone, epitestosterone, androsterone, and 5β-pregnane-3α,17α,20α-triol was fully separated on a C4 column under high-temperature elution with water as the sole eluent. The accuracy for isotope analysis (±0.5 ‰) was around 20 μg g–1 for testosterone, epitestosterone (79 ng steroid absolute on column), and 30 μg g–1 for 19-norandrosterone, androsterone, and 5β-pregnane-3α,17α,20α-triol (119 ng steroid absolute on column). The app...

  • Carbon isotope ratio measurements of glyphosate and AMPA by liquid chromatography coupled to isotope ratio Mass Spectrometry
    Analytical and Bioanalytical Chemistry, 2013
    Co-Authors: Dorothea Kujawinski, J. Benjamin Wolbert, Lijun Zhang, Maik Jochmann, David Widory, Nicole Baran, Torsten C Schmidt
    Abstract:

    The interest in compound-specific isotope analysis for product authenticity control and source differentiation in environmental sciences has grown rapidly during the last decade. However, the isotopic analysis of very polar analytes is a challenging task due to the lack of suitable chromatographic separation techniques which can be used coupled to isotope ratio Mass Spectrometry. In this work, we present the first method to measure carbon isotope compositions of the widely applied herbicide glyphosate and its metabolite aminomethylphosphonic acid (AMPA) by liquid chromatography coupled to isotope ratio Mass Spectrometry. We demonstrate that this analysis can be carried out either in cation exchange or in reversed-phase separation modes. The reversed-phase separation yields a better performance in terms of resolution compared with the cation exchange method. The measurement of commercial glyphosate herbicide samples show its principal applicability and reveals a wide range of δ^13C values between −24 and −34 ‰ for different manufacturers. The absolute minimum amounts required to perform a precise and accurate determination of carbon isotope compositions of glyphosate and AMPA were in the sub-microgram range. The method proposed is sensitive enough to further perform the experiments that are necessary to better understand the carbon isotope fractionation associated to the natural degradation of glyphosate into AMPA. Furthermore, it can be used for contaminant source allocation and product authenticity as well.

  • Carbon isotope ratio measurements of glyphosate and AMPA by liquid chromatography coupled to isotope ratio Mass Spectrometry
    Analytical and Bioanalytical Chemistry, 2013
    Co-Authors: Dorothea Kujawinski, J. Benjamin Wolbert, Lijun Zhang, Maik Jochmann, David Widory, Nicole Baran, Torsten C Schmidt
    Abstract:

    The interest in compound-specific isotope analysis for product authenticity control and source differentiation in environmental sciences has grown rapidly during the last decade. However, the isotopic analysis of very polar analytes is a challenging task due to the lack of suitable chromatographic separation techniques which can be used coupled to isotope ratio Mass Spectrometry. In this work, we present the first method to measure carbon isotope compositions of the widely applied herbicide glyphosate and its metabolite aminomethylphosphonic acid (AMPA) by liquid chromatography coupled to isotope ratio Mass Spectrometry. We demonstrate that this analysis can be carried out either in cation exchange or in reversed-phase separation modes. The reversed-phase separation yields a better performance in terms of resolution compared with the cation exchange method. The measurement of commercial glyphosate herbicide samples show its principal applicability and reveals a wide range of delta C-13 values between -24 and -34 aEuro degrees for different manufacturers. The absolute minimum amounts required to perform a precise and accurate determination of carbon isotope compositions of glyphosate and AMPA were in the sub-microgram range. The method proposed is sensitive enough to further perform the experiments that are necessary to better understand the carbon isotope fractionation associated to the natural degradation of glyphosate into AMPA. Furthermore, it can be used for contaminant source allocation and product authenticity as well.

  • High-temperature reversed-phase liquid chromatography coupled to isotope ratio Mass Spectrometry.
    Rapid communications in mass spectrometry : RCM, 2011
    Co-Authors: Lijun Zhang, Dorothea Kujawinski, Maik Jochmann, Torsten C Schmidt
    Abstract:

    Compound-specific isotope analysis (CSIA) by liquid chromatography coupled to isotope ratio Mass Spectrometry (LC/IRMS) has until now been based on ion-exchange separation. In this work, high-temperature reversed-phase liquid chromatography was coupled to, and for the first time carefully evaluated for, isotope ratio Mass Spectrometry (HT-LC/IRMS) with four different stationary phases. Under isothermal and temperature gradient conditions, the column bleed of XBridge C18 (up to 180 °C), Acquity C18 (up to 200 °C), Triart C18 (up to 150 °C), and Zirchrom PBD (up to 150 °C) had no influence on the precision and accuracy of δ13C measurements, demonstrating the suitability of these columns for HT-LC/IRMS analysis. Increasing the temperature during the LC/IRMS analysis of caffeine on two C18 columns was observed to result in shortened analysis time. The detection limit of HT-RPLC/IRMS obtained for caffeine was 30 mg L–1 (corresponding to 12.4 nmol carbon on-column). Temperature-programmed LC/IRMS (i) accomplished complete separation of a mixture of caffeine derivatives and a mixture of phenols and (ii) did not affect the precision and accuracy of δ13C measurements compared with flow injection analysis without a column. With temperature-programmed LC/IRMS, some compounds that coelute at room temperature could be baseline resolved and analyzed for their individual δ13C values, leading to an important extension of the application range of CSIA. Copyright © 2011 John Wiley & Sons, Ltd.

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