Application of high resolution fast atom bombardment and constant B/E ratio linked scanning to the identification and analysis of acylcarnitines in metabolic disease

Acylcarnitines, a biologically important group of metabolites which have thus far eluded characterization by mass spectrometry, exhibit very intense fast atom bombardment mass spectra dominated by parent cations. The combination of high resolution selected ion detection and daughter ion analysis using the linked scan at constant B/E ratio has enabled the unequivocal identification of the acylcarnitines in the urine of children with propionic acidemia, methylmalonic aciduria and Reye's Syndrome. Quantitative analysis of acetylcarnitine and propionylcarnitine in selected samples was accomplished by isotope dilution, utilizing (2H3)acetyl- and (2H5)propionylcarnitines as internal standards. These techniques will allow assessment of the therapeutic use of L-carnitine in these disorders.