Center for Forensic Hair Analytics, Zurich Institute of Forensic Medicine, University of Zurich, Zurich 8006, Switzerland.
Analytics, Zurich Forensic Science Institute, Zurich 8004, Switzerland.
J Anal Toxicol. 2024 Nov 15;48(9):672-683. doi: 10.1093/jat/bkae064.
As cocaine (COC) is not only incorporated into hair via blood following ingestion but also by external contamination, hair samples are commonly tested for COC metabolites to prove ingestion. However, COC metabolites can also be present as degradation products in typical street COC samples. The present study investigates minor hydroxycocaine (OH-COC) metabolites p- and m-OH-COC together with p- and m-hydroxybenzoylecgonine (OH-BE) in seized COC (n = 200) and hair samples from routine case work (n = 2389). Analytical results of hair samples were interpreted using an established decision model for the differentiation between actual use and external contamination using metabolic ratios (metabolite to COC). They were further examined concerning background of request, hair color, body site of sample collection, sex, and metabolic ratios of the main metabolites [benzoylecgonine (BE), norcocaine (NC), and cocaethylene (CE)]. All seized COC samples were positive for p- and m-OH-COC with a maximum percentage of 0.025% and 0.052%, respectively; p- and m-OH-BE were detected in 55% and 56% of samples with a maximum percentage of 0.044% and 0.024%, respectively. Analytical results of 424 hair samples (17.7%) were interpreted as being predominantly from contamination; the majority of these samples were from traffic medicine cases (83.7%). Metabolic ratios of minor OH-COC metabolites were significantly higher in hair samples interpreted as originating from use than in samples interpreted as caused by contamination. Metabolic ratios for OH-COCs were significantly higher in forensic cases compared to abstinence controls and also in black hair compared to blond/gray hair. However, this was not the case for OH-BE metabolic ratios. No statistical difference was observed with regard to the donor's sex. OH-COC metabolic ratios increased significantly with increasing ratios of NC and CE to COC, respectively. The study demonstrates that OH-COC metabolites (including thresholds for their metabolic ratios) must be used for a reliable interpretation of positive COC results in hair samples.
可卡因（COC）不仅通过摄入后随血液进入毛发，也会通过外部污染进入毛发，因此通常会检测毛发样本中的 COC 代谢物来证明摄入情况。然而，COC 代谢物也可能作为降解产物存在于典型的街头 COC 样本中。本研究调查了在缴获的 COC（n=200）和常规案件工作中的毛发样本（n=2389）中发现的微量羟基可卡因（OH-COC）代谢物对-和间-OH-COC 以及对-和间-羟基苯甲酰古柯碱（OH-BE）。使用建立的决策模型，通过代谢比（代谢物与 COC 的比值）来区分实际使用和外部污染，对毛发样本的分析结果进行解释。进一步检查了请求背景、毛发颜色、样本采集部位、性别以及主要代谢物（苯甲酰古柯碱（BE）、去甲可卡因（NC）和古柯乙基（CE））的代谢比。所有缴获的 COC 样本均呈对-和间-OH-COC 阳性，最大百分比分别为 0.025%和 0.052%；55%的样本中检测到对-和间-OH-BE，最大百分比分别为 0.044%和 0.024%。424 个毛发样本（17.7%）的分析结果被解释为主要来自污染；这些样本大多数来自交通医学案例（83.7%）。在被解释为使用来源的毛发样本中，微量 OH-COC 代谢物的代谢比明显高于被解释为污染来源的样本。与禁欲对照相比，法医案例中 OH-COC 的代谢比明显更高，与金发/灰发相比，黑发中 OH-COC 的代谢比也更高。然而，OH-BE 代谢比则并非如此。在供体性别方面没有观察到统计学差异。OH-COC 代谢比随着 NC 和 CE 与 COC 的比值分别增加而显著增加。该研究表明，OH-COC 代谢物（包括其代谢比的阈值）必须用于可靠解释毛发样本中 COC 阳性结果。
