Assay of the Concentration and 13C Enrichment of Acetate and Acetyl-CoA by Gas Chromatography-Mass Spectrometry

We present two techniques for determining the concentration and 13C enrichment of acetate in biological fluids. After the sample has been spiked with an internal standard of [2,2,2, 2H 3,1- 13C]acetate, acetate is first enzymatically converted to acetyl-coenzyme A, which is chemically converted to acetylglycine. The latter is analyzed by gas chromatography-mass spectrometry, either as a methyl ester by positive chemical ionization or as a pentafluorobenzyl ester by negative chemical ionization. The mole percentage enrichment of tissue acetyl-CoA can also be assayed after conversion to acetylglycine pentafluorobenzyl ester.