A study on the stability of anhydroecgonine methyl ester (crack biomarker), benzoylecgonine, and cocaine in human urine

Abstract

Background: Typically, urine and other biological tissues have been analyzed for cocaine (COC) and/or metabolites to detect COC usage. COC undergoes numerous biotransformation and degradation reactions. Crack smokers are exposed to anhydroecgonine methyl ester (AME), which can be used as an analytical marker for crack smoking. The stability of this analyte in human urine has not been studied. In the body, COC is rapidly converted to metabolites by enzymatic and chemical processes, the major urinary metabolite being benzoylecgonine (BE). Objectives: This study was carried out in order to determine the effects of time and temperature on the stability of cocaine/crack metabolites in human urine. Methods: The stability of AME, BE and COC in urine was investigated using samples of urine stored in freezers and refrigerators. The analytes were extracted from urine using a solid-phase extraction technique and analyzed by gas chromatography-flame ionization detection method. Results: COC concentrations decreased while BE concentrations increased. AME concentrations remained stable. Conclusions: The temperature and the duration of storage are decisive in COC hydrolyzing. This study suggests that AME concentrations are not correlated to either storage duration or with storage temperature and AME is more stable than COC.