title: Analysis of drugs of abuse in human plasma using microextraction by packed sorbents and ultra-high-performance liquid chromatography.
abstract: A miniaturized and simple method based on digitally programmed microextraction by packed sorbent (eVol®-MEPS) coupled to ultra-performance liquid chromatography (UPLC) has been developed for quantitative determination of three synthetic cathinones and seven conventional drugs of abuse and metabolites. The influence of several extraction parameters, such as washing and elution solvents were tested. In addition important variables affecting MEPS performance, namely sample volume, sorbent drying time, washing solvent volume, elution volume, number of extraction cycles, sorbent phase and pH, were evaluated using an asymmetrical screening design. The optimal experimental conditions involved 300μL of plasma, loading 10×100μL of sample through a C8/SCX sorbent in a MEPS syringe placed in the semi-automatic eVol®system, washing using 150μL H2O:MeOH (90:10, v/v), drying for 0.5min and elution using 200μL dichloromethane:2-propanol:ammonium hydroxide (78:20:2, v/v/v). The drugs separation was achieved using an ACQUITY BEH Shield RP18 column (2.1mm×100mm×1.7μm) in 3min. Under optimized conditions the proposed method was validated in terms of selectivity, linearity, limits of detection (LOD) and quantitation (LOQ), precision and matrix effect, using standard addition calibration. The combination of MEPS and UPLC provides a method for the primary screening of the analytes in 18min with excellent recoveries at three concentration levels, ranging between 80 and 104% (relative standard deviation <11%). The developed methodology has been successfully applied to plasma samples from polydrug abusers.
authors.affiliation: Institute of Forensic Sciences, Forensic Toxicology Service, Faculty of Medicine, University of Santiago de Compostela, 15782 Santiago de Compostela, Spain.
authors.forename: P
authors.initials: P
authors.lastname: Fernández
authors.affiliation: Department of Analytical Chemistry, Faculty of Chemistry, University of Santiago de Compostela, 15782 Santiago de Compostela, Spain.
authors.forename: M
authors.initials: M
authors.lastname: González
authors.affiliation: Institute of Forensic Sciences, Forensic Toxicology Service, Faculty of Medicine, University of Santiago de Compostela, 15782 Santiago de Compostela, Spain.
authors.forename: M
authors.initials: M
authors.lastname: Regenjo
authors.affiliation: Department of Analytical Chemistry, Faculty of Chemistry, University of Santiago de Compostela, 15782 Santiago de Compostela, Spain.
authors.forename: A M
authors.initials: AM
authors.lastname: Ares
authors.affiliation: Drug Addiction Assistance Unit, Monforte de Lemos, 27400 Lugo, Spain.
authors.forename: A M
authors.initials: AM
authors.lastname: Fernández
authors.affiliation: Department of Analytical Chemistry, Faculty of Chemistry, University of Santiago de Compostela, 15782 Santiago de Compostela, Spain.
authors.forename: R A
authors.initials: RA
authors.lastname: Lorenzo
authors.affiliation: Department of Analytical Chemistry, Faculty of Chemistry, University of Santiago de Compostela, 15782 Santiago de Compostela, Spain. Electronic address: tuchi.carro@usc.es.
authors.forename: A M
authors.initials: AM
authors.lastname: Carro
mesh_terms: D002138:Calibration; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D002853:Chromatography, Liquid; D006801:Humans; D013287:Illicit Drugs / Q000097:blood*; D057230:Limit of Detection; D011619:Psychotropic Drugs / Q000097:blood*; D052617:Solid Phase Microextraction / Q000379:methods*; D015813:Substance Abuse Detection / Q000379:methods*
chemical_list: D013287:Illicit Drugs; D011619:Psychotropic Drugs
keywords: Cathinones; Drugs of abuse; Microextraction by packed sorbent; Plasma; Ultra-performance-liquid chromatography