Automated solid-phase extraction and two-step derivatisation for simultaneous analysis of basic illicit drugs in serum by GC/MS

A combination of automated solid-phase extraction (SPE) and subsequent two- step derivatisation has been developed fur the simultaneous analysis of bas ic drugs of abuse and cocaine metabolites in serum samples. Substances incl uded in this procedure are morphine, codeine, methadone, cocaine, benzoylec gonine, methylecgonine, amphetamine, methamphetamine, MDMA, MDEA and MDA. S PE with mixed-mode cartridges (RP-C8 and cation-exchange) was fully automat ed with a Zymark RapidTrace SPE rebut. GC/MS analysis was performed after d erivatisation with a new two-step reaction by trifluoroacetic anhydride and 2,2,3,3,3-pentafluoropropanol. High recoveries (> 85%) with high reproduci bility (CV 1.1-3.8%) were found for all drugs. High correlation coefficient s (r > 0.998) were obtained due to the addition of deuterated standards pri or to extraction. Experience obtained over 2 years of applying this method to drug analysis in serum is discussed.