A previously published gas chromatography-mass spectrometry method (3, 4) was used to verify the absence of the following amphetamine-related compounds: amfepramone, amphetamine, benzodioxazoylbutanamine, benzphetamine, clobenzorex, dexfenfluramine, dimethoxybromoamphetamine, dimethoxymethylamphetamine, fencamfamin, fenproporex, mefenorex, methamphetamine, methoxyphenamine
, methylbenzodioxazolylbutanamine, methylenedioxyamphetamine, methylenedioxyethamphetamine, methylenedioxymethamphetamine, methylphenidate, 4methylthioamphetamine, norephedrine, norfenfluramine, phentermine, and pseudoephedrine.
An internal standard solution (50 [micro]L), comprising racemic methoxyphenamine (400 mg/L) and amphetamine (200 mg/L) in methanol, was added to each 5 mL of the calibrator, volunteer, and quality-control [prepared in batches by adding aqueous (R,S)-MDMA and (R,S)MDA to urine] samples.
Internal standard solution (50 [micro]L) containing racemic methoxyphenamine (4 mg/L) and amphetamine (1 mg/L) in water was added to 2 mL of each calibrator, volunteer, and quality-control sample [prepared in batches by the addition of aqueous (R,S)-MDMA and (R,S)-MDA stock solutions to plasma].
The diagnostic ions chosen for quantitative purposes were m/z 162 for MDMA, MDA, and amphetamine and m/z 148 for methoxyphenamine. Calibration curves were constructed by plotting peak height ratios of the selected ions of each analyte derivative to those of the selected internal standard derivative against the concentration of each analyte enantiomer.