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J Anal Toxicol. 2022 Oct 14;46(8):844-851. doi: 10.1093/jat/bkac051.
Immunoassay procedures, such as enzyme-linked immunosorbent assay (ELISA), are widely used for screening samples in both driving under the influence of drugs (DUID) and postmortem (PM) investigations. While these are sensitive and widely used techniques, they lack specificity compared to more novel instrumental screening platforms. In this study, the cross-reactivities of several cannabinoid isomers and related compounds were evaluated in whole blood using the Cannabinoids Direct ELISA kit from Immunalysis. The compounds of interest were supplemented individually at three different concentrations, ranging from 10 to 100 ng/mL or 10 to 1,000 ng/mL depending on analyte, to determine initial feasibility. Compounds exhibiting cross-reactivity were then tested to create dose-response curves to calculate the percent cross-reactivity. The cross-reactivity was determined to be 200% for delta-8-carboxy-tetrahydrocannabinol (THC) (delta-8-carboxy-THC), 25% for delta-9,11-THC, 13% for delta-10-THC, 7% for delta-6a(10a)-THC, 3% for THC-O-acetate and 0.5% for tetrahydrocannabiphorol. To determine potential impacts on forensic laboratory casework, a review of DUID and PM casework was also performed. From November 2020 to June 2021, a random sampling of DUID and PM cases was selected monthly and evaluated for the presence of cannabinoid isomer(s) in the absence of a reportable delta-9-carboxy-THC result. While validated techniques for the identification and confirmation of these isomer(s) did not exist at the time of routine testing, delta-8-carboxy-THC was believed to be the most common isomer finding based on current testing capability. This study demonstrated a noticeable increase in the presence of isomeric cannabinoid compounds in both forensic DUID and PM casework sampled during this period and suggests potential impacts for clinical casework as well.
免疫分析程序，如酶联免疫吸附测定（ELISA），广泛用于药物影响下驾驶（DUID）和死后（PM）调查中的样本筛选。虽然这些技术灵敏且应用广泛，但与更新型的仪器筛选平台相比，它们缺乏特异性。在这项研究中，使用 Immunalysis 的 Cannabinoids Direct ELISA 试剂盒评估了几种大麻素异构体和相关化合物在全血中的交叉反应性。根据分析物的不同，将感兴趣的化合物以三种不同的浓度单独补充，浓度范围为 10 至 100ng/mL 或 10 至 1,000ng/mL，以确定初始可行性。然后测试表现出交叉反应性的化合物，以创建剂量-反应曲线来计算交叉反应百分比。交叉反应性被确定为 delta-8-羧基-四氢大麻酚（THC）（delta-8-羧基-THC）为 200%，delta-9,11-THC 为 25%，delta-10-THC 为 13%，delta-6a(10a)-THC 为 7%，THC-O-乙酸酯为 3%，四氢大麻酚为 0.5%。为了确定对法医实验室案例工作的潜在影响，还对 DUID 和 PM 案例进行了审查。从 2020 年 11 月到 2021 年 6 月，每月随机选择 DUID 和 PM 案例进行采样，并评估在没有报告 delta-9-羧基-THC 结果的情况下是否存在大麻素异构体。虽然在常规测试时不存在用于这些异构体的鉴定和确认的验证技术，但根据当前的测试能力，delta-8-羧基-THC 被认为是最常见的异构体发现。本研究表明，在此期间采样的法医 DUID 和 PM 案例中异源大麻素化合物的存在明显增加，并表明临床案例工作也可能受到影响。
