Abstract: Studies on the Analysis of Meperidine Urinary Metabolites in ManShen Min;Shen Baohua;Xiang Ping(Institute of Forensic Sciences,Ministry of Justice,Shanghai 200063,China)Abstract:A GC/MS(EI.PCI)procedure for the determination of meperidine and its main four metabolites in human urine is described.Meperidine and its metabolism were extracted with diethyl ether or chloroform from urin samples at PH 11.The residue,upon evaporation of the extract to dryness, was resolved with methanol and another residue was derivatized with acetic anhydride,and then analysed by GC/MS.This method represents the mass spectra of the four metabolites of meperidine and major fragment pathways.Keywords:meperidine,metabolism,GC/MS