title: Sensitive method for detection of cocaine and associated analytes by liquid chromatography-tandem mass spectrometry in urine.
abstract: Cocaine (COC) is a potent CNS stimulant that is metabolized to benzoylecgonine (BE) and further metabolized to minor metabolites such as m-hydroxybenzoylecgonine (m-HOBE). COC is also metabolized to norcocaine (NC). Cocaethylene (CE) is formed when cocaine and ethyl alcohol are used simultaneously. Anhydroecgonine methyl ester (AEME) is a unique marker following smoked cocaine, and anhydroecgonine ethyl ester (AEEE) is found in cocaine smokers who also use ethyl alcohol. We developed a liquid chromatography-tandem mass spectrometry (LC-MS-MS) method for the detection and quantitation of COC, BE, NC, CE, m-HOBE, AEME, and AEEE in urine. Two hundred samples previously analyzed by gas chromatography (GC) coupled with MS were extracted using solid-phase extraction. Chromatographic separation was achieved using a gradient consisting of mobile phase A [20 mM ammonium formate (pH 2.7)] and mobile phase B (methanol/acetonitrile, 50:50), an XDB-C(8) (50 x 2.1 mm, 1.8 microm) column and a flow rate of 270 microL/min. Concentrations were calculated by comparing the peak-area with the internal standard and plotted against a standard curve. The assay displayed linearity from 1.0 to 100 ng/mL. Within- and between-run coefficients of variation were < 10% throughout the linear range. A method comparison between GC-MS and LC-MS-MS showed good correlation for COC (r(2) = 0.982) and BE (r(2) = 0.955). We report here on a sensitive method to identify clinically and forensically relevant cocaine and associated analytes at concentrations as low as 1.0 ng/mL.
authors.affiliation: Toxicology and Drug Monitoring Laboratory, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota, USA. Langman.loralie@mayo.edu
authors.forename: Loralie J
authors.initials: LJ
authors.lastname: Langman
authors.forename: Matthew W
authors.initials: MW
authors.lastname: Bjergum
authors.forename: Christopher L
authors.initials: CL
authors.lastname: Williamson
authors.forename: Frank W
authors.initials: FW
authors.lastname: Crow
mesh_terms: D002851:Chromatography, High Pressure Liquid; D003042:Cocaine / Q000031:analogs & derivatives / Q000652:urine*; D019970:Cocaine-Related Disorders / Q000175:diagnosis / Q000652:urine*; D018765:Dopamine Uptake Inhibitors / Q000652:urine*; D000431:Ethanol / Q000097:blood; D008401:Gas Chromatography-Mass Spectrometry; D006801:Humans; D015203:Reproducibility of Results; D052616:Solid Phase Extraction; D021241:Spectrometry, Mass, Electrospray Ionization; D015813:Substance Abuse Detection / Q000379:methods*; D053719:Tandem Mass Spectrometry
chemical_list: D018765:Dopamine Uptake Inhibitors; C085009:3-hydroxybenzoylecgonine; D000431:Ethanol; C008671:norcocaine; C068464:anhydroecgonine methyl ester; C005618:benzoylecgonine; D003042:Cocaine; C081641:ethyl ecgonine