SIMULTANEOUS ANALYSIS OF PLASMA-FREE FATTY-ACIDS AND THEIR 3-HYDROXY ANALOGS IN FATTY-ACID BETA-OXIDATION DISORDERS

We present a new derivatization procedure for the simultaneous gas chr omatographic-mass spectrometric analysis of free fatty acids and 3-hyd roxyfatty acids in plasma. Derivatization of target compounds involved trifluoroacetylation of hydroxyl groups and tert-butyldimethylsilylat ion of the carboxyl groups. This new derivatization procedure had the advantage of allowing the complete baseline separation of free fatty a cids and 3-hydroxyfatty acids while the superior gas chromatographic a nd mass spectrometric properties of teut-butyldimethylsilyl derivative s remained unchanged, permitting a sensitive analysis of the target co mpounds. Thirty-nine plasma samples from control subjects and patients with known defects of mitochondrial fatty acid beta-oxidation were an alyzed. A characteristic increase of long-chain 3-hydroxyfatty acids w as observed for all of the long-chain 3-hydroxyacyl-CoA dehydrogenase- deficient and mitochondrial trifunctional protein-deficient plasma sam ples. For medium-chain acyl-CoA dehydrogenase deficiency and very-long -chain acyl-CoA dehydrogenase deficiency, decenoic and tetradecenoic a cids, respectively, were the main abnormal fatty acids, whereas the mu ltiple acyl-CoA dehydrogenase-deficient patients showed variable incre ases of these unusual intermediates. The results showed that this sele ctive and sensitive method is a powerful tool in the diagnosis and mon itoring of mitochondrial fatty acid beta-oxidation disorders.