Measurement of carnitine precursors, epsilon-trimethyllysine and gamma-butyrobetaine in human serum by tandem mass spectrometry

Methods using tandem mass spectrometry for measurement of epsilon-trimethyl lysine and gamma-butyrobetaine in human serum are described. Precursor ion scan analysis of a methylated sample was applied for gamma-butyrobetaine me asurement. However, for epsilon-trimethyllysine measurement, homoarginine i nterfered with the methylated sample during precursor ion scan analysis. To overcome this interference, the sample was propylated and acetylated prior to precursor ion scan analysis. The obtained values resembled those obtain ed by enzymatic or HPLC measurement. Using tandem mass spectrometry, all me mbers of the carnitine family, free carnitine, acylcarnitines, gamma-butyro betaine, epsilon-trimethyllysine can be analyzed in 0.1 ml of serum. Thus, the proposed method appears to be suitable for clinical application, especi ally in the pediatric field. (C) 1999 Elsevier Science B.V. All rights rese rved.