Detection of amphetamine and methamphetamine in urine by gas chromatography/mass spectrometry following derivatization with (-)-menthyl chloroformate.

A gas chromatography/mass spectrometry assay was developed for the detection of amphetamine and methamphetamine in urine. These drugs were detected as carbamate derivatives following reaction with (-)-menthyl chloroformate. Selected ion monitoring of the 226, 182, and 227 dalton ions for amphetamine and the 240, 102, and 196 dalton ions for methamphetamine provided positive analyte identification. Quantitative values obtained by isotope dilution mass spectrometry displayed a linear response from below 50 to above 6,000 ng/mL. Differentiation of over-the-counter (R)-methamphetamine from illicit (S)-methamphetamine was accomplished by chromatographic separation of the diastereomeric derivatives on an achiral column. No interferences were observed from ephedrine, pseudoephedrine, phentermine, phenylpropanolamine, or 2-phenylethylamine.