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High pressure effects in high‐field asymmetric waveform ion mobility spectrometry
Author(s) -
Wang Yonghuan,
Wang Xiaozhi,
Li Lingfen,
Chen Chilai,
Xu Tianbai,
Wang Tao,
Luo Jikui
Publication year - 2016
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/rcm.7663
Subject(s) - chemistry , ion mobility spectrometry , ion , electric field , waveform , analytical chemistry (journal) , voltage , atmospheric pressure , dispersion (optics) , electrical mobility , ambient pressure , chromatography , thermodynamics , optics , physics , organic chemistry , quantum mechanics , oceanography , geology
Rationale High‐Field Asymmetric Waveform Ion Mobility Spectrometry (FAIMS) is an analytical technique based on the principle of non‐linear electric field dependence of coefficient of mobility of ions for separation that was originally conceived in the Soviet Union in the early 1980s. Being well developed over the past decades, FAIMS has become an efficient method for the separation and characterization of gas‐phase ions at ambient pressure, often in air, to detect trace amounts of chemical species including explosives, toxic chemicals, chemical warfare agents and other compounds. However the resolution of FAIMS and ion separation capability need to be improved for more applications of the technique. Methods The effects of above‐ambient pressure varying from 1 to 3 atm on peak position, resolving power, peak width, and peak intensity are investigated theoretically and experimentally using micro‐fabricated planar FAIMS in purified air. Results Peak positions, varying with pressure in a way as a function of dispersion voltage, could be simplified by expressing both compensation and dispersion fields in Townsend units for E/N, the ratio of electric field intensity (E) to the gas number density (N). Conclusions It is demonstrated that ion Townsend‐scale peak positions remain unchanged for a range of pressures investigated, implying that the higher the pressure is, stronger compensation and separation fields are needed within limits of air breakdown field. Increase in pressure is found to separate ions that could not be distinguished in ambient pressure, which could be interpreted as the differentials of ions' peak compensation voltage expanded wider than the dilation of peak widths leading to resolving power enhancement with pressure. Increase in pressure can also result in an increase in peak intensity.