A survey of extraction techniques for drugs of abuse in urine

• Published in: Forensic science international Vol. 119; no. 1; pp. 23 - 27
• Main Authors: Wilson, J.F, Smith, B.L, Toseland, P.A, Watson, I.D, Williams, J, Thomson, A.H, Capps, N.E, Sweeney, G, Sandle, L.N
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ireland Ltd 01.06.2001; Elsevier; Elsevier Limited
• Subjects: Acidification; Amfetamine; Amphetamines - urine; Biological and medical sciences; British Isles; Chi-Square Distribution; Chromatography; Cocaine; Cocaine - analogs & derivatives; Cocaine - urine; Drug abuse; Drug addictions; Drugs; Forensic sciences; Humans; Immunoassay; Laboratories; Laboratories - classification; Laboratories - standards; Liquid–liquid extraction; Medical sciences; Morphine; Morphine - urine; Narcotics - urine; Quality assessment; Quality Assurance, Health Care; Quality control; Questionnaires; Sensitivity and Specificity; Solid phase extraction; Solid phases; Substance Abuse Detection - methods; Substance Abuse Detection - standards; Substance-Related Disorders - diagnosis; Substance-Related Disorders - urine; Surveys and Questionnaires; Toxicology; United Kingdom; Urine; United Kingdom > UK; United States > US; Solid phase extraction; Amfetamine; Morphine; Liquid–liquid extraction; Cocaine; Amphetamine derivatives; Human; Urine; Liquid liquid extraction; Opiates; Medical screening; Survey; Laboratory investigations; Drug of abuse; Technique
• ISSN: 0379-0738; 1872-6283
• DOI: 10.1016/S0379-0738(00)00383-2

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.