Determination of amphetamine, methamphetamine and desmethyldeprenyl in human plasma by gas chromatography/negative ion chemical ionization mass spectrometry

A sensitive and specific assay for the quantitative determination of amphetamine, methamphetamine and desmethyldeprenyl in human plasma specimens is described. Electron capture/negative ion chemical ionization gas chromatography/mass spectrometry is used to determine the extracted plasma concentrations of the three target compounds as their N‐heptafluorobutyryl derivatives. Quantitation is performed by stable isotope dilution using d6‐amphetamine and d6‐methamphetamine as internal standards. Selected ion monitoring of the [M – HF]− ions of both the analytes and internal standards results in minimum quantifiable limits of 0.10 ng ml−1 for both amphetamine and methamphetamine and 0.25 ng ml−1 for desmethyldeprenyl. Excellent linearity (r = 0.998) up to at least 5.00 ng ml−1 is demonstrated.