title: Development of magnetic molecularly imprinted polymers for solid phase extraction of cocaine and metabolites in urine before high performance liquid chromatography - tandem mass spectrometry.
abstract: A magnetic molecularly imprinted polymer (MMIP) has been synthesized and applied for cocaine (COC) and metabolites (benzoylecgonine, BZE; cocaethylene, CE; and ecgonine methyl ester, EME) recognition/pre-concentration in urine samples. The MMIP has been prepared using COC as a template molecule, ethylene dimethacrylate (EDMA) as a functional monomer, divinylbenzene (DVB) as a cross-linker, Fe3O4 magnetite as a magnetic component, and 2,2'-azobisisobutyronitrile (AIBN) as an initiator. The best results (MIP layer on the surface of the magnetic nanoparticles) and physical properties of the prepared MMIP were obtained when assisting the synthesis procedure with ultrasounds (325W, 37kHz, 30°C, 4h). After solid phase extraction (SPE) with the prepared adsorbent material, analytes were determined by high performance liquid chromatography - tandem mass spectrometry (HPLC-MS/MS). Variables affecting the SPE process (batch mode) were fully evaluated. Optimum retention of analytes (1.8mL of urine and 50mg of MMIP) was achieved by fixing the urine pH at 5.5 (use of a KH2PO4/NaOH, pH 5.5 buffer solution), and magnetic stirring (25°C, 700rpm) for 10min. Elution was performed by using 2mL of a dichloromethane/2-propanol/ammonium hydroxide (75:20:5) mixture under ultrasounds (325W, 35kHz, room temperature) for 5min. The method was validated according to the guidance for bioanalytical method validation of the US Department of Health and Human Services, Food and Drug Administration. The detection limits were in the range of 0.39-1.4ngL(-1). The relative standard deviations of intra- and inter-day tests ranged from 5 to 11% and from 3 to 11%, respectively. Analytical recoveries were in the range of 79-106% when spiking drug-free urine samples at three concentration levels. Good results were also obtained after analyzing an FDT +25% control material. The applicability of the method was proved for screening/quantifying COC, BZE, CE and EME in several samples from poly-drug abusers.
authors.affiliation: Department of Analytical Chemistry, Nutrition and Bromatology, Faculty of Chemistry, University of Santiago de Compostela, Avenida das Ciencias, s/n, 15782 Santiago de Compostela, Spain.
authors.forename: Juan
authors.initials: J
authors.lastname: Sánchez-González
authors.affiliation: Department of Pathologic Anatomy and Forensic Sciences, Faculty of Medicine, University of Santiago de Compostela, Rúa de San Francisco, s/n, 15782 Santiago de Compostela, Spain.
authors.forename: María
authors.initials: M
authors.lastname: Jesús Tabernero
authors.affiliation: Department of Pathologic Anatomy and Forensic Sciences, Faculty of Medicine, University of Santiago de Compostela, Rúa de San Francisco, s/n, 15782 Santiago de Compostela, Spain.
authors.forename: Ana María
authors.initials: AM
authors.lastname: Bermejo
authors.affiliation: Department of Analytical Chemistry, Nutrition and Bromatology, Faculty of Chemistry, University of Santiago de Compostela, Avenida das Ciencias, s/n, 15782 Santiago de Compostela, Spain.
authors.forename: Pilar
authors.initials: P
authors.lastname: Bermejo-Barrera
authors.affiliation: Department of Analytical Chemistry, Nutrition and Bromatology, Faculty of Chemistry, University of Santiago de Compostela, Avenida das Ciencias, s/n, 15782 Santiago de Compostela, Spain. Electronic address: antonio.moreda@usc.es.
authors.forename: Antonio
authors.initials: A
authors.lastname: Moreda-Piñeiro
mesh_terms: D002851:Chromatography, High Pressure Liquid; D003042:Cocaine / Q000031:analogs & derivatives* / Q000652:urine; D052203:Ferrosoferric Oxide / Q000737:chemistry; D006801:Humans; D057230:Limit of Detection; D060328:Magnetic Phenomena; D008689:Methacrylates / Q000737:chemistry; D054802:Molecular Imprinting; D009570:Nitriles / Q000737:chemistry; D011092:Polyethylene Glycols / Q000737:chemistry; D052616:Solid Phase Extraction / Q000379:methods; D053719:Tandem Mass Spectrometry; D000069453:Ultrasonic Waves; D014753:Vinyl Compounds / Q000737:chemistry
chemical_list: D008689:Methacrylates; D009570:Nitriles; D014753:Vinyl Compounds; D011092:Polyethylene Glycols; C005618:benzoylecgonine; C004919:ethylene dimethacrylate; C066444:cocaethylene; C004526:azobis(isobutyronitrile); D003042:Cocaine; C004985:divinyl benzene; D052203:Ferrosoferric Oxide; C034524:ecgonine methyl ester
keywords: Cocaine; High performance liquid chromatography tandem mass spectrometry; Human urine; Magnetic molecularly imprinted polymer