Baker Jacquelyn E, Jenkins Amanda J
Biology Department, John Carroll University, University Heights, OH, USA.
Am J Forensic Med Pathol. 2008 Jun;29(2):141-4. doi: 10.1097/PAF.0b013e318174e7ab.
Testing for the presence of cocaine (COC) is common in postmortem and clinical laboratories. COC use may be detected by screening urine specimens for COC metabolite. In the forensic arena, screening positive results are confirmed by a more specific and sensitive technique, such as gas chromatography-mass spectrometry. This article reports the case of an individual who died of COC intoxication but whose immunoassay screen (EMIT) for COC metabolite was negative. Gas chromatography-mass spectrometry analysis of the urine detected benzoylecgonine (BE) at a concentration of 75 ng/mL and COC at 55 ng/mL. These concentrations explain the negative screening result since the cutoff concentration of the assay was 300 ng/mL for BE. The reported cross reactivity with COC was 25,000 ng/mL. However, heart blood concentrations of COC and BE were 18,330 and 8640 ng/mL, respectively. The results from this case provide evidence that an EMIT test alone may fail to detect COC use. Individuals utilizing results of drug screening by immunoassay must be aware of the limitations of this testing methodology.
在尸检和临床实验室中，检测可卡因（COC）的存在很常见。通过筛查尿液样本中的COC代谢物可以检测出是否使用了COC。在法医领域，筛查阳性结果会通过更特异、更灵敏的技术（如气相色谱 - 质谱联用）来确认。本文报告了一例死于COC中毒但COC代谢物免疫分析法（EMIT）筛查呈阴性的个体案例。尿液的气相色谱 - 质谱联用分析检测到苯甲酰爱康宁（BE）浓度为75 ng/mL，COC浓度为55 ng/mL。由于该检测方法对BE的截断浓度为300 ng/mL，所以这些浓度解释了筛查结果为阴性的原因。报告显示该方法与COC的交叉反应性为25,000 ng/mL。然而，心血中COC和BE的浓度分别为18,330 ng/mL和8640 ng/mL。该案例结果表明仅靠EMIT检测可能无法检测出是否使用了COC。使用免疫分析法进行药物筛查结果的人员必须了解这种检测方法的局限性。
