Abstract High-field Nuclear Magnetic Resonance (NMR) spectroscopy combined with multivariate analysis techniques have been used extensively in several fields particularly, metabolomics and food quality assessment. In contrast, low-field Fourier transform NMR instruments are a relatively new analytical platform and recent studies have shown its potential application for forensic narcotic identification. In this study Principal Component Analysis (PCA) and Orthogonal Partial Least Squares Discriminant Analysis (OPLS-DA) were applied on spectra data from both low-field (43 MHz) and high-field (300 MHz) NMR of two key precursors to fentanyl, N-phenethyl-4-piperidone (NPP) and 4-anilino-N-phenethylpiperidine (ANPP). Three different methods were employed for the synthesis of these two precursors – the Siegfried, Valdez and One-Pot methods. The application of low-field NMR spectroscopy combined with multivariate analysis allowed successful classification of fentanyl precursors, NPP and ANPP, based on each synthetic method’s unique impurity profile. This approach supports the possibility of low-field NMR being employed by law enforcement for forensic attribution of clandestine fentanyl and its precursors to a specific synthetic method.

中文翻译：

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通过低场核磁共振波谱数据的多变量分析对芬太尼前体进行分类

摘要 高场核磁共振 (NMR) 光谱结合多变量分析技术已广泛应用于多个领域，特别是代谢组学和食品质量评估。相比之下，低场傅立叶变换 NMR 仪器是一种相对较新的分析平台，最近的研究表明其在法医麻醉品鉴定方面具有潜在应用。在本研究中，主要成分分析 (PCA) 和正交偏最小二乘判别分析 (OPLS-DA) 应用于芬太尼的两种关键前体的低场 (43 MHz) 和高场 (300 MHz) NMR 光谱数据, N-苯乙基-4-哌啶酮 (NPP) 和 4-苯胺基-N-苯乙基哌啶 (ANPP)。这两种前体的合成采用了三种不同的方法——齐格弗里德法、瓦尔迪兹法和一锅法。低场 NMR 光谱的应用与多变量分析相结合，可以根据每种合成方法的独特杂质谱成功地对芬太尼前体、NPP 和 ANPP 进行分类。这种方法支持执法部门使用低场 NMR 对秘密芬太尼及其前体进行法医归属于特定合成方法的可能性。