Rapid detection of tert -butoxycarbonyl-methamphetamine by direct analysis in real time time-of-flight mass spectrometry.

Purpose: Phenethylamines constitute the majority of drug-related arrests in Japan. Recently, the smuggling of tert -butoxycarbonyl ( t -Boc)-protected phenethylamines has become of increasing concern, because of the difficult identification of these masked substances.

Methods: In this study, a rapid and accurate method for the detection of t -Boc-methamphetamine ( t -Boc-MP) by direct analysis in real time-time-of-flight-mass spectrometry (DART-TOF-MS) was developed. The efficiency of the method was evaluated by comparison with conventional gas chromatography-MS (GC-MS) and liquid chromatography-TOF-MS (LC-TOF-MS) techniques.

Results: During GC-MS analysis of t -Boc-MP, MP was generated in the injection port, which can lead to an analytical error. In the LC-TOF-MS spectrum, fragment ions were detected, which were generated by McLafferty rearrangement in the ion source. On the other hand, in the DART-TOF-MS analysis of t -Boc-MP, pyrolysis could be suppressed by using a micro-syringe injection method, and the fragment ions generated by McLafferty rearrangement were still observed. Moreover, protonated t -Boc-MP could be detected.

Conclusions: Hence, DART-TOF-MS provides a rapid and accurate method for the detection of t -Boc-MP, allowing suppression of the pyrolysis reaction and identification of both fragment ions and protonated t -Boc-MP. To our knowledge, this is the first report for detecting t -Boc-MP by MS techniques.