ORGANIC-ACID PROFILING BY DIRECT TREATMENT OF DEPROTEINIZED PLASMA WITH ETHYL CHLOROFORMATE

Carboxylic acids in plasma or serum can be conveniently determined by capillary gas chromatography (GC) following treatment with ethyl chlor oformate (ECF). The mixed organic solvent used for plasma deproteiniza tion is also suitable as medium for the subsequent reaction step. Thus , isolation of the compounds of interest is not necessary. Before trea tment of the supernatant with ECF, the neutral lipids and amino acids are removed easily by hexane extraction and cation-exchange chromatogr aphy. Ketocarboxylic acids do not require a preliminary oximation. Cap illary columns with a length of 15 m and a polar silicone phase proved to be ideal for the separation of mixtures of derivatized keto-, hydr oxy-, mono- and dicarboxylic acids. The run time is less than 30 min.