title: Simultaneous analysis of cocaine and its metabolites in urine by capillary electrophoresis-electrospray mass spectrometry using a pressurized liquid junction nanoflow interface.
abstract: A new method for the simultaneous separation of cocaine and four metabolites in urine by CE-ESI-MS via a pressurized nanoliquid junction interface was developed. The resolution of cocaine, cocaethylene, benzoylecgonine, norcocaine, and ecgonine methyl ester was achieved in a polyvinyl-alcohol-coated capillary with 75 μm id × 50 cm total length, using a 15 mM ammonium formate electrolyte solution (pH 9.5) in less than 15 min. In addition, to enhance sensitivity, a field-amplified sample injection (FASI) was evaluated in terms of injection time and sample solvent composition. The limits of detection achieved with the FASI method ranged from 1.5 to 10 ng/mL for all the compounds. The detection of the studied compounds was performed using an ion-trap mass spectrometer in a positive ionization mode. A mixture of methanol:water (80:20 v/v) containing 0.1% v/v of formic acid was employed as spray liquid and delivered at ~200 nL/min. Under optimal CE-MS conditions, linearity was assessed in the concentration range of interest for all analytes with correlation coefficients r² ≥ 0.9913. Intra- and inter-day precision provided a relative standard deviation lower than 1.54% for migration times and lower than 12.15% for peak areas. Finally, urine samples, spiked with the standard mixture, were extracted using a solid-phase extraction procedure and injected under FASI conditions, providing recoveries from 80% to 94% for all analytes.
authors.affiliation: Institute of Analytical Chemistry, Czech Academy of Sciences, Brno, Czech Republic.
authors.forename: Věra
authors.initials: V
authors.lastname: Hezinová
authors.forename: Zeineb
authors.initials: Z
authors.lastname: Aturki
authors.forename: Karel
authors.initials: K
authors.lastname: Klepárník
authors.forename: Giovanni
authors.initials: G
authors.lastname: D'Orazio
authors.forename: František
authors.initials: F
authors.lastname: Foret
authors.forename: Salvatore
authors.initials: S
authors.lastname: Fanali
mesh_terms: D003042:Cocaine / Q000378:metabolism* / Q000652:urine*; D019075:Electrophoresis, Capillary / Q000295:instrumentation / Q000379:methods*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D036103:Nanotechnology / Q000295:instrumentation* / Q000379:methods; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D021241:Spectrometry, Mass, Electrospray Ionization / Q000295:instrumentation / Q000379:methods*
chemical_list: D003042:Cocaine