Identification of 3-Hydroxyisovalerylcarnitine in the Urine of a Patient with Multiple Carboxylase Deficiency

Abstract

Analysis of acylcarnitines in urine by fast atom bombardment/mass spectrometry (FAB/MS) is a prerequisite for diagnosis of organic acidurias.! M+ ion masses of several putative acylcarnitine methylesters were identified. In this study, we analysed urine samples of a patient with multiple carboxylase deficiency. The signals obtained by FAB/MS were consistent with the methylesters of acetylcarnitine (m/z218), propionylcarnitine (m/z232), C4 (m/z246), C~:I (m/z258) and C~ (m/z260) acylcarnitines, octenoylcarnitine (m/z300), octanoylcarnitine (m/z302), nonanoylcarnitine (m/z316), adipylcarnitine (m/z318) and unknown compound (m/z276). However, the signal in m/z 276 has not been reported. We hydrolyzed acylcarnitines by mild alkaline hydrolysis and identified the liberated acids by gas chromatography/mass spectrometry (GC/MS). From the retention time and the characteristic mass spectrum, we identified the 3-hydroxyisovaleric acid trimethylsilyl derivative.