Detection of methamphetamine in urine stains.

Objective: The aim of this study is to determine the stability of methamphetamine in urine stains on two materials (gauze and filter paper) which were stored for up to 24 weeks in different temperatures and environmental conditions. Methods: One ml of 10 different concentrations of positive methamphetamine urine samples were prepared for study by staining each samples on gauze sponge and filter paper. Each set of urine stains were stored at 0C, 4C, room temperature and outdoor (avoiding water and rain exposure). Urine stains were eluted subsequently at different times as follows: immediately, 3 days, 1 week, 2 weeks, 4 weeks, 12 weeks and 24 weeks, respectively. Then, elution solvent was analyzed for methamphetamine concentration by TDx analyzer. Results: Methamphetamine concentrations of immediate urine stains on gauze were lower than that of urine in all concentrations. The urine stains on filter paper contained methamphetamine less than urine at a concentration below 5,000 ng/ml. Methamphetamine on gauze and filter paper stored at 0C and 4C did not change for 24 weeks. Being stored at room temperature and outdoor, methamphetamines on gauze and filter paper significantly decreased during 24 weeks. The amount of methamphetamines on gauze and filter paper at outdoor declined faster than at room temperature within the same time frame. Conclusions: Rethamphetamine recovered from urine stains on filter paper was higher than from gauze sponge. The amount of methamphetamine of urine stain on gauze and filter paper were stable when stored at 0C and 4C but at room temperature and outdoor they were continuously declined during 24 weeks.