Acetic acid isolated from cider vinegar and inorganically synthesized glacial acetic acid have markedly different intramolecular isotopic distributions of the stable carbon isotopes. Carbon-I2 is concentrated in the methyl group relative to the carboxyl group in the biologically produced acid. The reverse distribution is observed in the particular sample of glacial acetic acid examined here.

Abstract-The concentrations of carbon-I3 in the individual carbon atoms of 3-hydroxy-2-butanone (acetoin) from apple cider vinegar decrease with decreasing oxidation level in the sequence

Abstract-Acetobacter suboxydans, strain 8.3, was grown using ethanol, made by the hydration of ethylene, as the sole energy source. After the microorganism had oxidized some of the ethanol to acetic acid, the unassimilated alcohol and produced acetic acid were isolated from the supernatant. Carbon isotopic analyses of these compounds and the starting ethanol show: ( I ) the methyl carbon of the starting alcohol is enriched in carbon-I3 by 4.6 % relative to the hydroxyl carbon, (2) the starting alcohol contains 2%0 less carbon-13 than the unassimilated ethanol and (3) the carboxyl carbon of the acetic acid excreted by the A. suboxydans is enriched by 3.8 %o in carbon-I3 relative to the methyl carbon. These results support earlier findings which indicate that organisms preferentially utilize compounds enriched in carbon-I2 and tend to concentrate carbon-I2 in the reduced carbons relative to the oxidized carbons of metabolic products.

Gas-liquid-solid chromatography (GLSC) employing a poly-(phenyl ether) (PPE 20) liquid phase on graphitized carbon black (GCB) is applicable to the analyses of crude oils and distillates of sedimentary rocks. The elution of C4 to C40 hydrocarbons which consist of -alkanes, isoprenoid-type alkanes, steranes, olefins, and aromatic hydrocarbons can be handled in a single GC run. A GLSC column in tandem with a mass spectrometer provides an excellent means for the identification of geochemically significant organic compounds in complex natural mixtures,