Measurement of free and esterified carnitine in tissue extracts by high-performance liquid chromatography

A high-performance liquid chromatographic (HPLC) method for the determination of L-carnitine in clamped and frozen rat livers is described. L-carnitine + acetyl-CoA in equilibrium with acetyl-L-carnitine + CoASH Using the above enzymatic reaction, release of CoASH is stoichiometric with the L-carnitine added. The present method has made possible the determination of carnitine in liver tissues, which is difficult by the conventional enzymatic spectrophotometric method using 5,5'-dithiobis(2-nitrobenzoic acid), owing to acetyl-CoA hydrolysis during prolonged incubations at pH 7.8.