title: Analytical method for simultaneous determination of bulk and intramolecular (13) C-isotope compositions of acetic acid.
abstract: BACKGROUND
  Headspace 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 (δ(13) C value) of acetic acid.
  
  
  METHODS
  The δ(13) C values of carboxyl and methyl carbon were standardized using calibration curves constructed from the regression between the measured δ(13) C values and the δ(13) C values of working standards determined in a previous study. We applied this developed HS-SPME-GC/Py-GC/C-IRMS technique to commercial vinegars.
  
  
  RESULTS
  In one injection analysis, the bulk and intramolecular δ(13) C values of pure acetic acid standards can be obtained. The repeatability (1σ) of the bulk δ(13) C values is within ±0.4‰, and that of the δ(13) Ccarboxyl and δ(13) Cmethyl values is within ±0.6‰. The intramolecular δ(13) C values of acetic acid in vinegars exhibit a similar pattern. The average Δδ value (δ(13) CCOOH - δ(13) CCH3 ) is 4.3 ± 2.0‰.
  
  
  CONCLUSIONS
  The approach presented herein for the molecular and intramolecular δ(13) C 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.
authors.affiliation: Department of Environmental Science and Technology, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama, 226-8502, Japan.
authors.forename: Tarin
authors.identifier: http://orcid.org/0000-0002-0149-1417
authors.initials: T
authors.lastname: Nimmanwudipong
authors.affiliation: Earth-Life Science Institute (WPI-ELSI), Tokyo Institute of Technology, Meguro, Tokyo, 152-8551, Japan.
authors.forename: Alexis
authors.initials: A
authors.lastname: Gilbert
authors.affiliation: Department of Environmental Chemistry and Engineering, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama, 226-8502, Japan.
authors.forename: Keita
authors.initials: K
authors.lastname: Yamada
authors.affiliation: Department of Environmental Science and Technology, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama, 226-8502, Japan.|Earth-Life Science Institute (WPI-ELSI), Tokyo Institute of Technology, Meguro, Tokyo, 152-8551, Japan.|Department of Environmental Chemistry and Engineering, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama, 226-8502, Japan.
authors.forename: Naohiro
authors.initials: N
authors.lastname: Yoshida
mesh_terms: D019342:Acetic Acid / Q000032:analysis* / Q000737:chemistry*; D002247:Carbon Isotopes / Q000032:analysis*; D005504:Food Analysis; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods; D015203:Reproducibility of Results; D052617:Solid Phase Microextraction / Q000379:methods
chemical_list: D002247:Carbon Isotopes; D019342:Acetic Acid