Forensic Chemistry Center, Office of Regulatory Science, Office of Regulatory Affairs, U.S. Food & Drug Administration, Cincinnati, OH, 45237.
J Forensic Sci. 2020 Sep;65(5):1443-1449. doi: 10.1111/1556-4029.14457. Epub 2020 May 26.
A simple, quick, selective, sensitive, and effective field-friendly method capable of being used by nonexperts has been developed for detecting mitragynine in Mitragyna speciosa (kratom) using surface-enhanced Raman spectroscopy (SERS). Over 100 samples and blanks (known to be either positive or negative for the presence of mitragynine) were examined in duplicate using five identical handheld Raman spectrometers, which provided a data set of over 1,000 examinations. Based on the results of these analyses, the method yielded a true-positive rate of 99.3%, a true-negative rate of 97.9%, a false-positive rate of 2.1%, and a false-negative rate of 0.7%. The average minimum detectable concentration (C ) of mitragynine that reproducibly yielded a match for one of the library spectra on all five instruments was determined to be 342 ng/mL (ppb). This C value is a conservative estimate considering that the extraction process was not fully optimized by this study, which was not necessary since the C value achieved was well below typical mitragynine concentrations in kratom (1.3-2.3%). The method is ideal (i) for prioritizing samples for additional testing using other more time-consuming laboratory-based techniques needed to detect and quantify mitragynine and (ii) for field use at international mail facility (IMF) satellite laboratories to help interdict kratom and prevent this dangerous product from reaching the U.S. supply chain.
已经开发出一种简单、快速、选择性强、灵敏度高且适用于非专业人士的现场友好型方法，用于使用表面增强拉曼光谱（SERS）检测美托咪定在美托咪定（Kratom）中的存在。使用五台相同的手持式拉曼光谱仪对超过 100 个样本和空白样本（已知是否存在美托咪定）进行了重复检查，提供了超过 1000 次检查的数据组。基于这些分析的结果，该方法的真阳性率为 99.3%，真阴性率为 97.9%，假阳性率为 2.1%，假阴性率为 0.7%。可重复性地在所有五台仪器上与库光谱之一匹配的美托咪定的平均最小可检测浓度（C）被确定为 342ng/mL（ppb）。考虑到提取过程未通过本研究完全优化，因此该 C 值是保守估计，因为本研究中实现的 C 值远低于 Kratom 中美托咪定的典型浓度（1.3-2.3%）。该方法非常理想，（i）可用于优先选择其他需要检测和定量美托咪定的更耗时的实验室技术进行额外测试的样本，以及（ii）可用于国际邮件处理（IMF）卫星实验室的现场使用，以帮助阻止 Kratom 并防止这种危险产品进入美国供应链。
