title: Analysis of drugs of abuse in human plasma by dispersive liquid-liquid microextraction and high-performance liquid chromatography.
abstract: Opioids and cocaine are widely used at present, both for recreational purposes and as drugs of abuse. This raises the need to develop new analytical methods specifically designed for the simultaneous detection of several drugs of abuse in biological samples. In this work, dispersive liquid-liquid microextraction (DLLME) was assessed as a new sample treatment for the simultaneous extraction of morphine (MOR), 6-acetylmorphine (6AM), cocaine (COC), benzoylecgonine (BZE) and methadone (MET) from human plasma. Preliminary assays were done before developing an experimental design based on a Uniform Network Doehlert which allowed the optimum extraction conditions to be identified, namely: a volume of extractant solvent (chloroform) and dispersant solvent (acetonitrile) of 220 µl and 3.2 ml, respectively; 0.2 g of NaCl as a salting-out additive; pH 10.6 and ultrasound stirring for 3.5 min. The resulting extracts were analyzed by high-performance liquid chromatography with photodiode array detection (HPLC-PDA), using an XBridge® RP18 column (250 × 4.6 mm i.d., 5 µm particle size). Calibration graphs were linear over the concentration range 0.1-10 µg ml⁻¹, and detection limits ranged from 13.9 to 28.5 ng ml⁻¹. Precision calculated at three different concentration levels in plasma was included in the range 0.1-6.8% RSD. Recoveries of the five drugs were all higher than 84% on average. Finally the proposed method was successfully applied to 22 plasma samples from heroin, cocaine and/or methadone users, and the most frequently detected drug was benzoylecgonine, followed by methadone, cocaine and morphine.
authors.affiliation: Institute of Legal Medicine, Forensic Toxicology Service, Faculty of Medicine, 15782, Santiago de Compostela, Spain.
authors.forename: P
authors.initials: P
authors.lastname: Fernández
authors.forename: M
authors.initials: M
authors.lastname: Regenjo
authors.forename: A M
authors.initials: AM
authors.lastname: Bermejo
authors.forename: A M
authors.initials: AM
authors.lastname: Fernández
authors.forename: R A
authors.initials: RA
authors.lastname: Lorenzo
authors.forename: A M
authors.initials: AM
authors.lastname: Carro
mesh_terms: D053000:Analytic Sample Preparation Methods; D002851:Chromatography, High Pressure Liquid; D056148:Chromatography, Reverse-Phase; D003042:Cocaine / Q000031:analogs & derivatives / Q000097:blood* / Q000737:chemistry; D006801:Humans; D006863:Hydrogen-Ion Concentration; D013287:Illicit Drugs / Q000097:blood* / Q000737:chemistry; D057230:Limit of Detection; D059627:Liquid Phase Microextraction; D008691:Methadone / Q000097:blood* / Q000737:chemistry / Q000627:therapeutic use; D009020:Morphine / Q000097:blood* / Q000737:chemistry; D009022:Morphine Derivatives / Q000097:blood / Q000737:chemistry; D058850:Opiate Substitution Treatment; D010783:Photometry; D015203:Reproducibility of Results; D012995:Solubility; D013056:Spectrophotometry, Ultraviolet; D015813:Substance Abuse Detection; D019966:Substance-Related Disorders / Q000097:blood* / Q000188:drug therapy; D014465:Ultrasonics / Q000379:methods
chemical_list: D013287:Illicit Drugs; D009022:Morphine Derivatives; C005618:benzoylecgonine; D009020:Morphine; D003042:Cocaine; C026979:6-O-monoacetylmorphine; D008691:Methadone
keywords: DLLME; HPLC-PDA; drugs of abuse; experimental design; plasma