title: Fast gas chromatography/mass spectrometric assay for the validated quantitative determination of methadone and the primary metabolite EDDP in whole blood.
abstract: A toxicological analysis was developed and validated for simultaneous screening and quantification of methadone (METH) and its primary metabolite 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP). The method employs microscale liquid-liquid extraction (microLLE) and direct injection of a separated aliquot of the organic layer into a gas chromatography/mass spectrometric (GC/MS) system without any other pre-treatment stages. A fast GC/MS runtime (total 5.8 min; METH, Rt = 3.55 min; EDDP, Rt = 3.40 min) combined with rapid sample preparation allowed cost-efficient and routinely applicable performance with a low amount of manual work. The validated parameters included: linearity (25-1000 ng mL(-1) both; R(METH)2 = 0.998 and R(EDDP)2 = 0.997), accuracy (Bias(METH): from -0.05 to 11.3%, Bias(EDDP): from 1.11 to 4.37%); intra and inter-assay precision (RSD(METH): from 2.4 to 3.9%, from 4.89 to 10.3%; RSD(EDDP): from 4.50 to 6.20%, from 4.57 to 15.2%), extraction efficiency (METH = 95.5%; EDDP = 90.6%), LOQ(Meth,EDDP) = 25 ng mL(-1). Samples were stable for at least 25 h and no selectivity problems or baseline interference were observed. The method should be applicable for identifying and quantitative confirmation of possible misuse and/or illegal use of METH in toxicological cases.
authors.affiliation: National Public Health Institute, Drug Research Unit, Mannerheimintie 166, 00300 Helsinki, Finland. teemu.gunnar@ktl.fi
authors.forename: Teemu
authors.initials: T
authors.lastname: Gunnar
authors.forename: Tanja
authors.initials: T
authors.lastname: Eskola
authors.forename: Pirjo
authors.initials: P
authors.lastname: Lillsunde
mesh_terms: D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods; D008691:Methadone / Q000031:analogs & derivatives / Q000097:blood*; D015394:Molecular Structure; D011759:Pyrrolidines / Q000097:blood*; D012015:Reference Standards; D013997:Time Factors
chemical_list: D011759:Pyrrolidines; D008691:Methadone; C010724:2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine