Shu Irene, Alexander Amy, Jones Mary, Jones Joseph, Negrusz Adam
United States Drug Testing Laboratories, Inc., 1700 S Mount Prospect Rd., Des Plaines, IL 60018, United States.
United States Drug Testing Laboratories, Inc., 1700 S Mount Prospect Rd., Des Plaines, IL 60018, United States.
J Chromatogr B Analyt Technol Biomed Life Sci. 2016 Aug 15;1028:145-152. doi: 10.1016/j.jchromb.2016.06.015. Epub 2016 Jun 11.
Chiral separation is crucial for investigating methamphetamine positive cases. While (S)-(+)-enantiomer of methamphetamine (S-MAMP) is a schedule II controlled substance, (R)-(-)-enantiomer (R-MAMP) is an active ingredient of a few over-the-counter drugs in the United States. Among biological specimen types, hair provides greater detection window than blood, urine or oral fluid, and are therefore regarded with particular interest. Herein we describe a novel non-chiral liquid chromatography-tandem mass spectrometry (LC-MS/MS) method to directly determine methamphetamine enantiomeric composition (percentage) in hair specimens. Hair samples were washed once with acetone, powdered, incubated overnight at 53°C in 0.1M hydrochloric acid (HCl), and subjected to a solid phase extraction (SPE). The extracts were derivatized using Marfey's reagent at 53°C for 60min. The final mixture was analyzed by LC-MS/MS. Chromatographic separation was achieved using a C18 Kinetex analytical column and 60% (v/v) aqueous methanol as mobile phase (isocratic). Triple quadrupole mass spectrometer was equipped with an electro-spray ionization (ESI) source operating in negative mode and the chromatograms were acquired using a multiple-reaction monitoring (MRM) approach. The results were expressed as ratio of R- to S-MAMP and then derived to composition percentages without requiring quantitating each enantiomer. The method was precise and accurate across 0-100% S-composition at a range of 80-18,000pg/mg. The performance of the new method was compared with an (S)-(-)-N-trifluoroacetylprolyl chloride (S-TPC) derivatization and gas chromatography-mass spectrometry (GC-MS) method on authentic methamphetamine-positive hair samples. Not only the new Marfey's reagent approach presented satisfactory correlation with the S-TPC approach, but it also exhibited significantly improved quality (e.g., S/N) of the chromatograms. In summary, our protocol employs cost effective and minimally hazardous Marfey's reagent to derivatize trace amounts of methamphetamine extracted from hair samples and a non-chiral LC-MS/MS approach to separate and identify the two enantiomers. The method allows determination of the methamphetamine enantiomeric composition without requiring quantitation of each enantiomer and is therefore well suited for further investigate previously determined methamphetamine positive cases. This method represents a viable tool for evaluation of long-term drug exposure.
手性分离对于调查甲基苯丙胺阳性案例至关重要。虽然甲基苯丙胺的(S)-(+)-对映体（S-MAMP）是附表二管制物质，但(R)-(-)-对映体（R-MAMP）是美国一些非处方药的活性成分。在各种生物样本类型中，毛发提供的检测窗口期比血液、尿液或口腔液更长，因此受到特别关注。在此，我们描述了一种新型的非手性液相色谱-串联质谱（LC-MS/MS）方法，用于直接测定毛发样本中甲基苯丙胺对映体组成（百分比）。毛发样本用丙酮洗涤一次，研磨成粉末，在0.1M盐酸（HCl）中于53°C孵育过夜，然后进行固相萃取（SPE）。提取物在53°C下用Marfey试剂衍生化60分钟。最终混合物通过LC-MS/MS进行分析。使用C18 Kinetex分析柱和60%（v/v）的甲醇水溶液作为流动相（等度洗脱）实现色谱分离。三重四极杆质谱仪配备电喷雾电离（ESI）源，以负模式运行，色谱图采用多反应监测（MRM）方法采集。结果以R-MAMP与S-MAMP的比例表示，然后推导为组成百分比，无需对每种对映体进行定量。该方法在80 - 18,000pg/mg的范围内，在0 - 100% S-组成时精确且准确。将新方法的性能与(S)-(-)-N-三氟乙酰基脯氨酰氯（S-TPC）衍生化和气相色谱-质谱（GC-MS）方法在真实的甲基苯丙胺阳性毛发样本上进行了比较。新的Marfey试剂方法不仅与S-TPC方法具有良好的相关性，而且其色谱图的质量（如信噪比）也有显著提高。总之，我们的方案采用经济高效且危害最小的Marfey试剂对从毛发样本中提取的痕量甲基苯丙胺进行衍生化，并采用非手性LC-MS/MS方法分离和鉴定两种对映体。该方法无需对每种对映体进行定量即可测定甲基苯丙胺对映体组成，因此非常适合进一步调查先前确定的甲基苯丙胺阳性案例。此方法是评估长期药物暴露的一种可行工具。
