Direct detection of acetonitrile at the pptv level with photoinduced associative ionization time-of-flight mass spectrometry

Abstract

Photoionization mass spectrometry (PI-MS) has become a versatile tool in the real-time analysis of volatile organic compounds (VOCs) from the atmosphere or exhaled breath. However, some key species, e.g., acetonitrile,...

A Simple High-Flux Switchable VUV Lamp Based on an Electrodeless Fluorescent Lamp for SPI/PAI Mass Spectrometry

“…Photoinduced associative ionization (PAI) is a newer ionization pathway discovered in recent years that is intrinsically different from dopant-assisted photoionization. − During PAI, gaseous CH 2 Cl 2 initially absorbs VUV light and generates excited state CH 2 Cl 2 *, and then CH 2 Cl 2 * interacts with H 2 O and the analyte through an associative reaction to convert a proton from neutral H 2 O to the analyte. Because of the homogeneous mixing of the highly concentrated neutral reactants and the ultrafast reaction rate, PAI shows a very high ionization efficiency for a series of polar VOCs, e.g., oxygenated organics, organic amines, nitro compounds, sulfur ethers, and monoterpenes. − Due to the efficient utilization of both photonic and chemical energy, PAI can protonate some substances that have ionization energies higher than the photon energy, e.g., acetonitrile and methanol. , Therefore, PAI is considered an effective ionization method to improve the detection sensitivity and extend the range of detectable compounds of SPI-MS.…”

“…46−49 Due to the efficient utilization of both photonic and chemical energy, PAI can protonate some substances that have ionization energies higher than the photon energy, e.g., acetonitrile and methanol. 46,50 Therefore, PAI is considered an effective ionization method to improve the detection sensitivity and extend the range of detectable compounds of SPI-MS.…”