title: A survey of extraction techniques for drugs of abuse in urine.
abstract: Sixty nine participants in the United Kingdom national external quality assessment scheme for drugs of abuse in urine reported details of their sample extraction technique by questionnaire. Laboratories were categorised by differences in technique and their analytical test results compared for samples containing D-amfetamine 0.4 (4) and 0.8 (3) mg/l, morphine 0.4 (4) and 0.8 (4)mg/l, and benzoylecgonine 0.15/0.2 (2) and 0.45/0.5 (4) mg/l. Values in parentheses are numbers of samples. For amfetamine, there was no significant difference in the frequency of true positive results between liquid-liquid or solid phase extraction and the Toxi-Lab A system at 0.8 mg/l. Toxi-Lab A gave significantly fewer positives when operating below its specified threshold at 0.4 mg/l. Paradoxically, laboratories using >5 ml urine volume performed less well. Acidification of the extract before volume reduction gave significantly more true positives. For extraction of morphine, solid phase systems significantly outperformed both liquid-liquid and the Toxi-Lab A system at both 0.8 and 0.4 mg/l. No significant differences between extraction techniques were demonstrated for analysis of benzoylecgonine.
authors.affiliation: Department of Pharmacology, Therapeutics & Toxicology, University of Wales College of Medicine, Health Park, Cardiff, UK. wilsonjf@cardiff.ac.uk
authors.forename: J F
authors.initials: JF
authors.lastname: Wilson
authors.forename: B L
authors.initials: BL
authors.lastname: Smith
authors.forename: P A
authors.initials: PA
authors.lastname: Toseland
authors.forename: I D
authors.initials: ID
authors.lastname: Watson
authors.forename: J
authors.initials: J
authors.lastname: Williams
authors.forename: A H
authors.initials: AH
authors.lastname: Thomson
authors.forename: N E
authors.initials: NE
authors.lastname: Capps
authors.forename: G
authors.initials: G
authors.lastname: Sweeney
authors.forename: L N
authors.initials: LN
authors.lastname: Sandle
mesh_terms: D000662:Amphetamines / Q000652:urine; D016009:Chi-Square Distribution; D003042:Cocaine / Q000031:analogs & derivatives* / Q000652:urine; D006801:Humans; D007753:Laboratories / Q000145:classification / Q000592:standards; D009020:Morphine / Q000652:urine; D009294:Narcotics / Q000652:urine; D011785:Quality Assurance, Health Care; D012680:Sensitivity and Specificity; D015813:Substance Abuse Detection / Q000379:methods* / Q000592:standards; D019966:Substance-Related Disorders / Q000175:diagnosis* / Q000652:urine*; D011795:Surveys and Questionnaires; D006113:United Kingdom
chemical_list: D000662:Amphetamines; D009294:Narcotics; C005618:benzoylecgonine; D009020:Morphine; D003042:Cocaine