We analyzed stimulants in the urine by automated head-space gas chromatography. A 6-ml of urine-containing stimulants was pipetted into a 20 ml autosampler vial together with 0.5 ml of 20% sodium hydroxide and 3.5 g of potassium carbonate. After the vial was sealed and heated for 20 min at 80°C, 0.8 ml of the head space gas was injected into the gas chromatograph equipped with a FID and fusedsilica capillary column (DB-17 : 30 m×0.32 mm i.d., film thickness 0.5 μm), by using Hamilton gas tight syringe. Addition of potassium carbonate to the urine increased the detection limit 10 to 100 times. The calibration curves showed a linearity in the range of 0.1 to 15 μg/ml for methamphetamine and amphetamine. The relative standard deviations were 4.8% for methamphetamine and 4.1% for amphetamine when the stimulants concentration was 10 μg/ml. Detection limits of methamphetamine and amphetamine were 0.02 μg/ml and 0.05 μg/ml, respectively.
