Radial Electric Field Driven Collision-Induced Dissociation in a Miniature Continuous Atmospheric Pressure Interfaced Ion Trap Mass Spectrometer

Miniature ion trap mass spectrometry with the unique ability of tandem-in-time analysis is extensively used in public security and environmental pollution detection. In this study, a novel radial electric field driven collision-induced dissociation (REFD-CID) is presented with high fragmentation efficiency for different species by adjusting the float DC, the initial kinetic energy of ions, and the pressure in a miniature continuous atmospheric pressure interfaced ion trap mass spectrometer (CAPI-ITMS). It is noteworthy that multiple fragment ions ([M+H-nC₂H₄]⁺, where n = 1, 2, 3) of triethyl phosphate were observed with a single injection of ions. The underlying mechanism of the REFD-CID revealed that the enhanced radial electric field by modulation of the float DC drove ions toward regions of intense RF field where broadband heating and dissociation of ions took place through theoretical simulations. Finally, the REFD-CID was utilized to improve the instrument performances. The existence of reagent ions led to a severe space charge effect as the ion injection duration of the CAPI-ITMS was extended to enhance the sensitivity of aniline. Through selective fragmentation of reagent ions, peak broadening and mass shift were eliminated, and meanwhile, a 28-fold improvement of aniline in a signal-to-noise ratio was achieved with the ion injection duration varying from 50 to 2500 ms. Moreover, isomeric illicit drugs (JWH-018 and acetylcodeine) were distinguished by generating multiple characteristic fragment ions, demonstrating potential applications in the identification of synthetic illicit drugs.