Rapid screening method for methamphetamine in urine by colour reaction in a Sep-Pak C18 cartridge

A simple screening method for methamphetamine in urine by colour reaction was developed. Methamphetamine, which is quantitatively retained in a Sep-Pak C18 cartridge, is (after a clean-up procedure) coloured by Simon's reagent (consisting of sodium nitroprusside solution, sodium carbonate solution and acetaldehyde gas). The detection limit was 0.5 microgram/ml using 5 ml of urine sample. The results of the screening method agreed with those of thin-layer chromatography and gas chromatography-mass spectrometry.