Acylcarnitine analysis by tandem mass spectrometry.

Carnitine plays an essential role in fatty acid metabolism, as well as modulation of intracellular concentrations of free coenzyme A by esterification of acyl residues. Acylcarnitine analysis of various biological fluids is a sensitive method to detect >20 inborn errors of metabolism that result in abnormal accumulation of acylcarnitine species due to several organic acidemias and most fatty acid beta-oxidation disorders. In addition, acylcarnitine analysis may aid in monitoring treatment of known patients affected with these inborn errors of metabolism. This unit describes protocols that can be used to measure acylcarnitine species of various carbon chain lengths in several biological specimen types including plasma, dried blood and bile spots, and urine, by derivatization to butylesters and flow-injection electrospray ionization tandem mass spectrometry (ESI-MS/MS).