[Determination of amphetamines in human urine using microwave extraction-gas chromatography]

A method has been developed for the determination of methamphetamine (MA), 3,4-methylenedioxyamphetamine (MDA) and 3,4-methylenedioxymethamphetamine (MDMA) in human urine using microwave extraction-gas chromatography(GC). To improve the extraction efficiency, experimental parameters of the extraction, including extraction solvent and its amount, pH value of the urine sample, extraction time and temperature were investigated. The optimal conditions were as follows: the pH value of urine sample at pH 12, cyclohexane as extraction solvent, extraction at 40 degrees C for 10 min. The average recoveries of MA, MDA and MDMA with this extraction method were 92.25%, 85.94% and 91.50%, the relative standard deviations were 5.5%, 5.5% and 6.1%(n = 5), and the limits of detection were 10, 20 and 20 ng/mL, respectively. Using this method, MA, MDA and MDMA need not be derivatized and can be separated from the matrix. The results indicate that the developed method is rapid, accurate and sensitive, and can be used for the simultaneous determination of MA, MDA and MDMA in urine samples.