Detection of Pharmaceuticals by Nitrogen Direct Analysis in Real Time Mass Spectrometry

Direct analysis in real time. mass spectrometry (DART-MS) was usually employed as a novel method for fast screening of target compounds in complex matrix samples. However, nitrogen direct analysis in real time(N-2-DART) mass spectrometry(MS) analysis of labile compounds usually tends to be challenging be. cause of its low ionization energy and complex background signals. In the current study, N-2-DART ion source coupled with high resolution Orbitrap MS based on a make. up solvent approach, which was designed for analy. sis of pharmaceuticals sensitively and easily, was reported. The main parameters of ion source, including gas temperature, gas type, scan mode, and solvent effect, were studied. The results confirmed that, compared with conventional He. DART, N-2-DART could generate obviously different ions in positive ion mode. And the sensitivity obtained by N-2-DART was found to be comparable with that obtained by He. DART. Typical mecha. nisms including the reactions of oxidation and rearrangement in N-2-DART were also discussed in detail. For the purpose of further confirmation, theoretical calculation was employed to verify the feasibility of the rearrange. ment reaction. The results demonstrated that N-2-DART-MS could provide a rapid and reliable method for the identification of active ingredients in pharmaceuticals, and may be applicable to other mixtures.