GC‐MS Determination of Amphetamines in Human Urine

Abstract

An analytical method for the simultaneous determination of amphetamine (AP), methamphetamine (MA), 3,4‐methylenedioxyamphetamine (MDA), 3,4‐methylenedioxy‐methamphetamine (MDMA), and 3,4‐methylenedioxy‐ethamphetamine (MDEA) in urine, using gas chromatography–mass spectrometry (GC–MS), is proposed. The analytes were subjected to liquid–liquid extraction with 4∶1 (v/v) methylene chloride/isopropanol at pH 12, and derivatized with pentafluoropropionic anhydride (PFPA) and ethyl acetate. Calibration curves for the five analytes in methanol and urine were constructed over the range 0.5–5.0 µg·ml⁻¹, using their respective pentadeuterated analogues as internal standards. The average extraction recoveries from the urine were higher than 91% for the five amphetamines. The limits of detection and quantitation achieved were 2.02 and 6.74 ng·ml⁻¹ for AP; 0.56 and 1.88 ng·ml⁻¹ for MA; 2.74 and 9.13 ng·ml⁻¹ for MDA; 2.95 and 9.85 ng·ml⁻¹ for MDMA; and 5.41 and 18.03 ng·ml⁻¹ for MDEA. The accuracy was in the range ±4% and the coefficients of variation were less than 9% for all analytes. The analysis of real urine samples with the proposed method provided 24 positives for amphetamines, with the following average concentrations: 0.56 µg·ml⁻¹ for AP, 6.78 µg·ml⁻¹ for MA, 0.90 µg·ml⁻¹ for MDA, 8.78 µg·ml⁻¹ for MDMA, and 1.13 µg·ml⁻¹ for MDEA.

Keywords:

• Amphetamines
• human urine
• GC‐MS