Enantioselective determination of methadone and its main metabolite 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP) in serum, urine and hair by capillary electrophoresis

A capillary electrophoresis method has been developed for the enantioselective determination of methadone and its main metabolite 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP) in serum and urine. After addition of the internal standard diphenhydramine, the serum and urine samples were extracted at pH 9-10 with n-hexane. Different cyclodextrins were tested for use as chiral selectors. The best results for simultaneous separation of methadone and EDDP were obtained using heptakis-(2,6-di-O-methyl)-beta-cyclodextrin (DIMEB). Data on the accuracy and precision of the method are presented. The method was applied to serum, urine, and hair samples, from individuals undergoing methadone therapy, under consideration of multi-drug abuse.