Analytical method for simultaneous determination of bulk and intramolecular C-13-isotope compositions of acetic acid

作者：Nimmanwudipong Tarin^*; Gilbert Alexis; Yamada Keita; Yoshida Naohiro

来源：Rapid Communications in Mass Spectrometry, 2015, 29(24): 2337-2340.

DOI：10.1002/rcm.7398

RationaleHeadspace solid-phase microextraction (HS-SPME) combined with gas chromatography/pyrolysis-gas chromatography/combustion-isotope ratio mass spectrometry (GC/Py-GC/C-IRMS) was developed for the simultaneous determination of the intramolecular and molecular carbon-isotopic composition (C-13 value) of acetic acid.
MethodsThe C-13 values of carboxyl and methyl carbon were standardized using calibration curves constructed from the regression between the measured C-13 values and the C-13 values of working standards determined in a previous study. We applied this developed HS-SPME-GC/Py-GC/C-IRMS technique to commercial vinegars.
ResultsIn one injection analysis, the bulk and intramolecular C-13 values of pure acetic acid standards can be obtained. The repeatability (1 sigma) of the bulk C-13 values is within 0.4 parts per thousand, and that of the C-13(carboxyl) and C-13(methyl) values is within +/- 0.6 parts per thousand. The intramolecular C-13 values of acetic acid in vinegars exhibit a similar pattern. The average value (C-13(COOH) - C-13(CH3)) is 4.3 +/- 2.0 parts per thousand.
ConclusionsThe approach presented herein for the molecular and intramolecular C-13 determination of acetic acid avoids switching between configuration systems and thereby reduces systematic errors. It is expected to be useful for examining isotope fractionation associated with processes related to organic acid (bio)transformations.

• 出版日期2015-12-30