Abstract
A urine sample obtained from a phenothiazine user was examined to identify metabolites which caused false-positive result on a screening test for methamphetamine in urine based on the Simon's color test. The urine sample was processed by liquid-liquid extraction under mild alkaline condition, and the extract was analyzed by TLC using Simon's reagent as a visualization reagent. Two blue or violet spots were appeared on the TLC plate by this reagent, and were identified as norchlorpromazine sulfoxide and norpromethazine sulfoxide by mass spectrometry after purification of the spots. Both of these two compounds possess an aliphatic secondary amine moiety, and are known as the metabolites of chlorpromazine and promethazine. These metabolites in the above urine sample were also confirmed by HPLC and LC/MS analysis. A control urine sample spiked with these metabolites gave positive result on the above screening test, indicating that these metabolites were the substances which caused false-positive on the test.
