The gas chromatographic mass spectrometric determination of trifluoroacetic acid in biological fluid. Application to halothane metabolism.

The methyl ester of trifluoroacetic acid was prepared by reaction with N,N'-dimethylformamide dimethylacetal and was successfully passed through a gas chromatograph. Trifluoroacetic acid was detected by the use of gas chromatography and low and high resolution gas chromatography mass spectrometry in an acidic extract of an incubation medium containing microsomes, reduced nicotinamide adenine dinucleotide phosphate, oxygen and halothane. However, trifluoroacetic acid could not be detected when nicotinamide adenine dinucleotide or oxygen was omitted from the incubation system. From these results, it was proved that halothane is oxidatively metabolized to trifluoroacetic acid by hepatic microsomes.