Gas chromatography-mass spectrometry of saturated and unsaturated dicarboxylic acids in urine.

Saturated and unsaturated dicarboxylic acids in urine are analyzed within the total profile of organic acids, using the methyl ester derivatives. Twenty-three acids with two carboxyl groups were identified. The method is employed for comparative studies of the excretion of dicarboxylic acids by individuals with normal and with increased fatty acid oxidation. In the group of the unsaturated acids, the cis-trans isomers mesaconic acid and citraconic acid, the two isomers of 3-methylglutaconic acid and muconic acid are characterized by the mass spectra of their methyl esters. The saturated unbranched and even-numbered dicarboxylic acids are elevated during fasting and diabetic ketoacidosis. In the total profile of the organic acids, succinic and adipic acid are indicators for ketoacidotic states.