Quantitative assay of free and total carnitine using tandem mass spectrometry

A new, specific method for isotope dilution assay of total and free carnitine in urine has been developed. The method utilizes fast atom bombardment ionization with tandem mass spectrometry and requires minimal sample preparation. It compared well with radioenzymatic assay in terms of specificity, precision and accuracy, but was much more convenient in terms of analysis time and sample throughput. The new method is also applicable to the determination of free and short-chain total carnitine in plasma.