title: Hydrophilic interaction liquid chromatography-tandem mass spectrometry (HILIC-MS/MS) determination of cocaine and its metabolites benzoylecgonine, ecgonine methyl ester, and cocaethylene in hair samples.
abstract: This study reports the development and validation of a method using hydrophilic interaction liquid chromatography-tandem mass spectrometry (HILIC-MS/MS) for the analysis of cocaine and its metabolites benzoylecgonine (BE), ecgonine methyl ester (EME), and cocaethylene (CE) in hair samples. Decontamination was performed as follows: Firstly, the aliquot of hair was briefly rinsed with 2 mL dichloromethane, then was washed three times with 10 mL 0.01 M phosphate buffer, pH 6, for 15 min, followed by 2 mL 2-propanol for less than 2 min, and, finally, a last rinse with 2 mL dichloromethane was again done. Cocaine compounds were extracted from 10 mg of hair by incubation with 2 mL 0.1 M HCl at 50 °C for 12 h and purified by solid phase extraction with Oasis MCX cartridges. Analysis was performed by LC-MS/MS using an Atlantis HILIC silica chromatographic column. The method was fully validated. Linearity was established over the concentration range 0.020-10.0 ng/mg for cocaine (COC), 0.010-10.0 ng/mg for BE and CE, and 0.005-2.0 ng/mg for EME, and the correlation coefficients were all >0.99. Extraction efficiency was >70% for all analytes. Limits of detection were 0.0005 ng/mg for CE and 0.001 ng/mg for the other analytes (COC, BE, and EME). Lower limits of quantification were the lowest points of the calibration curves with acceptable accuracy and precision (coefficient of variation ≤20%). Intra- and inter-day imprecision ranged between 1.5% and 9.5% and 0.7% and 12.6%, respectively. Intra- and inter-day inaccuracy ranged from 0.5% to 12.3% and from 0.7% to 7.1%, respectively. With regard to matrix effects, suppression was <27.5% in all cases. The method was applied to the analysis of several samples derived from forensic cases.
authors.affiliation: Forensic Toxicology Service, Institute of Legal Medicine, University of Santiago de Compostela, San Francisco s/n, 15782, Santiago de Compostela, Spain. oscar.quintela@usc.es
authors.forename: Oscar
authors.initials: O
authors.lastname: Quintela
authors.forename: Elena
authors.initials: E
authors.lastname: Lendoiro
authors.forename: Angelines
authors.initials: A
authors.lastname: Cruz
authors.forename: Ana
authors.initials: A
authors.lastname: de Castro
authors.forename: Alfredo
authors.initials: A
authors.lastname: Quevedo
authors.forename: Carmen
authors.initials: C
authors.lastname: Jurado
authors.forename: Manuel
authors.initials: M
authors.lastname: López-Rivadulla
mesh_terms: D002138:Calibration; D002851:Chromatography, High Pressure Liquid; D003042:Cocaine / Q000031:analogs & derivatives* / Q000032:analysis* / Q000378:metabolism; D006197:Hair / Q000737:chemistry* / Q000378:metabolism*; D006801:Humans; D011786:Quality Control; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D052616:Solid Phase Extraction; D053719:Tandem Mass Spectrometry
chemical_list: C005618:benzoylecgonine; C066444:cocaethylene; D003042:Cocaine; C034524:ecgonine methyl ester