Sulfonium salts as derivatizing agents. 3. Quantitation of the cocaine metabolite benzoylecgonine in urine using gas chromatography with ion-pair extraction/on-column alkylation.

Recent studies have demonstrated the utility of quantitative assays for benzoylecgonine in assessing the efficacy of cocaine-dependence-treatment programs to determine if the amount of cocaine consumed has been reduced. We describe a simple gas chromatographic method for determining benzoylecgonine concentrations in urine. BZE is extracted from urine as an ion pair with tri-n-propylsulfonium ion. Injection into the heated injection port of the gas chromatograph results in thermal conversion of the ion pair to the n-propyl ester of BZE. Using the structural analogue of BZE, m-toluylecgonine, as the internal standard, the analysis is carried out on a (5% phenyl)methylpolysiloxane capillary column with nitrogen-phosphorus detection. There was a good correlation between BZE concentrations determined by gas chromatography-mass spectrometry and concentrations determined by the method described in this paper. Application to cocaine-dependence-treatment programs is discussed.

Cocaine metabolite kinetics in the newborn.

The study goal was to determine the half-life elimination of cocaine and benzoylecgonine (BZE) in the newborn. Three 0.3-mL blood samples were collected during the first day of life. Urine was collected once daily. Cocaine and BZE concentrations were determined by gas chromatography-mass spectrometry. An extraction method was developed for measuring low concentrations of cocaine and BZE in small (0.1 mL) blood samples. Cocaine had a half-life of 11.6 h in one subject. The half-life of BZE during the first day of life, based on blood data in 13 subjects, was 16 h (95% confidence interval [CI], 12.8 to 21.4 h). The half-life of BZE during the first week of life, based on urine data in 16 subjects, was 11.2 h (95% CI, 10.1 to 11.8 h). The novel extraction method for small blood sample volumes should be applicable to other basic drugs.

Gas chromatographic determination of methamphetamine and its metabolite amphetamine in human plasma and urine following conversion to N-propyl derivatives.

A gas chromatographic method for the simultaneous determination of methamphetamine and its metabolite amphetamine in human plasma and urine is described. The method utilizes reductive alkylation with propionaldehyde and sodium borohydride to produce N-propyl derivatives, which have excellent chromatographic properties. Structural analogs of the analytes, p-methylmethamphetamine and p-methylamphetamine, are used as internal standards. The method has good precision and accuracy for concentrations ranging from less than 10 ng/ml to 5000 ng/ml and has been used to measure plasma concentrations as part of a pharmacokinetic/pharmacodynamic study of methamphetamine in humans.