Center for Forensic Hair Analytics, Zurich Institute of Forensic Medicine, University of Zurich, Zurich, Switzerland.
Department of Psychiatry, Psychotherapy and Psychosomatics, Psychiatric Hospital of the University of Zurich, Switzerland.
J Anal Toxicol. 2019 Aug 23;43(7):543-552. doi: 10.1093/jat/bkz022.
Given that external contamination must be considered in hair analysis, there is still a demand for reliable tools to differentiate between incorporation of drugs into the hair as a result of drug consumption and of the hair shaft by external contamination. With the aim of establishing alternative discrimination parameters, some of the hydroxy metabolites of cocaine i.e., para- and meta-hydroxycocaine and para- and meta-hydroxybenzoylecgonine were measured together with cocaine, benzoylecgonine, cocaethylene, and norcocaine in five seized street cocaine samples and in hair samples from different cohorts: cohort 1 (in vivo external contamination study, n = 28), cohort 2 (individuals with self-reported cocaine use, n = 92), and cohort 3 (individuals with suspected cocaine use or contamination, n = 198). Statistical evaluation of the data of cohort 1 and 2 using ROC curves yielded metabolic ratios indicating cocaine use. Based on these results, a decision workflow was established for the discrimination between cocaine use and external contamination. The power of this approach was finally statistically validated across the different cohorts.
鉴于毛发分析中必须考虑到外部污染，因此仍然需要可靠的工具来区分药物摄入导致的药物在毛发中的掺入和毛发外部污染导致的药物在毛发中的掺入。为了建立替代的判别参数，我们一起测量了可卡因的一些羟基代谢物，即对-和间-羟基可卡因以及对-和间-羟基苯甲酰可卡因，以及可卡因、苯甲酰可卡因、古柯烷和去甲可卡因，这些物质取自五个缴获的街头可卡因样本和来自不同队列的毛发样本：队列 1（体内外部污染研究，n=28）、队列 2（自我报告可卡因使用者，n=92）和队列 3（疑似可卡因使用者或污染者，n=198）。使用 ROC 曲线对队列 1 和 2 的数据进行统计评估，得出了表明可卡因使用的代谢比率。基于这些结果，为了区分可卡因使用和外部污染，建立了决策工作流程。最后，通过对不同队列的统计验证，证明了这种方法的有效性。
