Development of methods of the gas chromatographic determination of phenylcarboxylic acids in blood serum and their adaptation to clinical laboratory conditions

A method has been developed for the determination of phenylcarboxylic acids (benzoic, p-hydroxyphenyllactic, p-hydroxyphenylacetic, phenyllactic, 3-phenylpropanoic, and phenylacetic) in blood serum by gas chromatography with a flame-ionization detector (FID). The quantitative characteristics of analysis obtained with the FID and mass spectrometric detectors are in the same range and exhibit common trends for different groups of samples. It has been shown that the reproducibility of the results increases with the addition of a stage of salting out to the sample preparation procedure. The accuracy of the results is estimated using the added-found method. A possibility of the application of widely used FID to the quantitative determination of phenylcarboxylic acids in blood serum has been demonstrated for routine clinical practice.