Quantification of amphetamine in urine: solid-phase extraction, polymeric-reagent derivatization and reversed-phase...

The concentration of amphetamine was determined in urine using solid-phase extraction, polymeric-reagent derivatization, and reversed-phase high-performance liquid chromatography with ultraviolet detection. To remove a majority of acidic and neutral compounds in urine, a solid-phase extraction was first performed on a sample spiked with the internal standard, 1-methyl-3-phenyl-propylamine. Because amphetamine has a relatively low molar absorptivity, the base was derivatized with a polymeric 1-hydroxybenzotriazole reagent containing a 3,5-dinitrobenzoate active ester. The limit of detection is 14 ng/ml, and the limit of quantification is 47 ng/ml. The calibration curve is linear from 0.01 to 4.0 micrograms/ml. The pooled relative standard deviation is +/- 5.5% for eight urine samples measured in duplicate. The average relative error (bias) is +2.2% when compared to gas chromatography-mass spectrometry.