Liquid chromatography combined with mass spectrometry for ¹³C isotopic analysis in life science research

Abstract

Among the different disciplines covered by mass spectrometry, measurement of 13 C/ 12 C isotopic ratio crosses a large section of disciplines from a tool revealing the origin of compounds to more recent approaches such as metabolomics and proteomics. Isotope ratio mass spectrometry (IRMS) and molecular mass spectrometry (MS) are the two most mature techniques for 13 C isotopic analysis of compounds, respectively, for high and lowisotopic precision. For the sample introduction, the coupling of gas chromatography (GC) to either IRMS or MS is state of the art technique for targeted isotopic analysis of volatile analytes. However, liquid chromatography (LC) also needs to be considered as a tool for the sample introduction into IRMS or MS for 13 C isotopic analyses of non-volatile analytes at natural abundance as well as for 13 C-labeled compounds. This review presents the past and the current processes used to perform 13 C isotopic analysis in combination with LC. It gives particular attention to the combination of LC with IRMS which started in the 1990's with the moving wire transport, then subsequently moved to the chemical reaction interface (CRI) and was made commercially available in 2004 with the wet chemical oxidation interface (LC-IRMS). The LC-IRMS method development is also discussed in this review, including the possible approaches for increasing selectivity and efficiency, for example, using a 100% aqueous mobile phase for the LC separation. In addition, applications for measuring 13 C isotopic enrichments using atmospheric pressure LC-MS instruments with a quadrupole, a time-of-flight, and an ion trap analyzer are also discussed as well as a LC-ICPMS using a prototype instrument with two quadrupoles. #

Isotope ratio mass spectrometry coupled to liquid and gas chromatography for wine ethanol characterization

“…At elevated temperature, water is similar, in terms of eluotropic strength, to a mixture of organic solvent and water. 26 In this case, ethanol characterization (repeatability and reproducibility) did not improve when the temperature was increased (up to 558C). For this reason, temperature control is not required, and room temperature (258C) was chosen as the working temperature.…”

“…A pivotal analytical challenge for coupling HPLC to IRMS is to find HPLC conditions that allow baseline separation of the molecules of interest from the other molecules in the mixture. 26 Furthermore, when studying 13 C/ 12 C ratios, one should not rule out the possibility that the different steps of the method may cause isotopic fractionation.…”

Carbon allocation and carbon isotope fluxes in the plant-soil-atmosphere continuum: a review

“…Xu et al, 2004;Gessler et al, 2009a) -is possible with modern continuous-flow coupling of liquid chromatography (LC-IRMS; cf. Godin et al, 2007) or gas chromatography (GC-IRMS; cf. Sessions, 2006) with isotope-ratio mass spectrometry and, when high levels of 13 C label are applied, also with LC-MS/MS (LC coupled to tandem mass spectrometer) systems.…”

Progress and challenges in using stable isotopes to trace plant carbon and water relations across scales

“…The IRMS has experienced technological and methodological development, particularly Compound Specific Isotope Analysis (CSIA), which includes IRMS coupled to Gas Chromatography-Combustion (GC-C-IRMS; MaierAugenstein, 1999) or Liquid Chromatography (LC-IRMS; Godin et al, 2007). This facilitates the analysis of different compounds such as structural and labile carbohydrates extracted from plant organs, leaf wax alkanes, phloem sap and soil fractions (see review by Sachse et al, 2012).…”