Journal of Forensic Medicine ›› 2022, Vol. 38 ›› Issue (6): 726-732.DOI: 10.12116/j.issn.1004-5619.2022.320102

• Original Articles • Previous Articles     Next Articles

Structure Analysis of the Interfering Substance N-methyl-2-phenylpropan-1-amine of Methamphetamine in Wastewater

Ting-ting ZHANG1(), Yu HUANG1, Xue-jun ZHANG2, Jie CHEN1, Zhen-dong HUA1()   

  1. 1.Key Laboratory of Drug Monitoring and Control, Drug Intelligence and Forensic Center, Ministry of Public Security, Beijing 100193, China
    2.Anti-drug Corps of Jiangxi Provincial Public Security Department, Nanchang 330038, China
  • Received:2022-01-25 Online:2022-12-25 Published:2022-12-28
  • Contact: Zhen-dong HUA

Abstract:

Objective To analyze the chemical structure of the interfering substance that affects the result of methamphetamine analysis in wastewater. Methods A combination of GC-MS and liquid chromatography-quadrupole time-of-flight mass spectrometry (LC-QTOF-MS) was used to analyze the mass spectrum characteristics of the interfering substance that affects the result of methamphetamine analysis and to infer its possible structure. Liquid chromatography-triple quadrupole-mass spectrometry (LC-TQ-MS) was used to confirm the control material. Results Using LC-QTOF-MS in positive electrospray ionization (ESI+) mode, the mass-to-charge ratio (m/z) of quasi-molecular ion in the MS1 mass spectrometry of interfering substance was identical to that of methamphetamine, indicating that the interfering substance was probably an isomer of methamphetamine. The MS2 mass spectra obtained at three collision energies of 15 V, 30 V and 45 V were highly similar to methamphetamine, suggesting that the interfering substance contained methylamino and benzyl groups. Further analysis using GC-MS in electron impact (EI) ionization mode showed that the base peak in the mass spectrum of the interfering substance was at m/z 44. The interfering substance was confirmed to be N-methyl-2-phenylpropan-1-amine by compared with the standard reference. Conclusion The chemical structure of N-methyl-2-phenylpropan-1-amine is highly similar to methamphetamine, which is easy to cause interference for the detection of trace amounts of methamphetamine in wastewater using LC-TQ-MS. Therefore, in the actual analysis, the chromatographic retention time can be used to distinguish between N-methyl-2-phenylpropan-1-amine and methamphetamine.

Key words: forensic medicine, toxicological analysis, methamphetamine, wastewater analysis, mass spectrometry, interfering substance, N-methyl-2-phenylpropan-1-amine (phenpromethamine)

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