Quantitative analysis for organic acids in biological samples: batch isolation followed by gas chromatographic-mass spectrometric analysis.

This new method for qualitative and quantitative determination of organic acids, aldehydes, and ketones in biological samples is effective for use with urine, plasma, and amniotic fluid, and it requires no deproteinization. Isolation by batch-wise liquid partition chromatography on silicic acid follows formation of the O-(2,3,4,5,6-pentafluorobenzyl)oximes of oxoacids, aldehydes, and ketones. The total organic acid content of the sample provides a rapid screening test for metabolic abnormality. A wide-bore, bonded-phase capillary column was used for quantitative gas chromatographic-mass spectrometric analysis, followed by automated identification and quantification. Analytical recoveries were quantitative for a wide variety of metabolites. Gas-chromatographic retention indices, discriminating ions, and control ranges in amniotic fluid, plasma, and urine of adult subjects were determined for 61 biologically important compounds.