Rapid Switching of Reagent Ions in Dopant-Assisted Positive Photoionization Ion Mobility Spectrometry for Highly Selective and Sensitive Ammonia Detection in Atmospheric Environments

作者：Jinlong Wang, Jiyou Fei, Mei Li, Wei Huang, Junyu Yang, Y. Q. Wang, Xueying Bai, Linlin Jiang, Peiran Song, Jinghua Li, Chuang Chen, Huaiwen Cang, Lei Hua, Haiyang Li · 发表于：Analytical Chemistry · 年份：2025 · DOI：10.1021/acs.analchem.5c03686 · 被引用次数：2 · 研究领域：Advanced Chemical Sensor Technologies、Atmospheric chemistry and aerosols、Mass Spectrometry Techniques and Applications

Ammonia (NH 3 ), a critical precursor in the atmospheric formation of fine particulate matter (particularly PM 2.5 ), poses significant environmental challenges by contributing to eutrophication and acidification as its concentration increases. Consequently, the real-time and accurate monitoring of atmospheric NH 3 is of great environmental and regulatory importance. In this study, an innovative technique for the rapid switching of reagent ions between (C 4 H 8 O) 2 H + and (H 2 O) n H + in dopant-assisted positive photoionization ion mobility spectrometry (DAPP-IMS) within 2 s by simply controlling the on–off of water dopant is proposed. This facilitates NH 3 detection under two distinct modes: high selectivity and high sensitivity. In the high-selectivity mode, 2-butanone is employed as the dopant, generating (C 4 H 8 O) 2 H + as the predominant reagent ion. Under these conditions, the method achieves a limit of detection (LOD) of 5 ppb, enabling selective quantification of NH 3 in complex matrices. To achieve high-sensitivity detection, we introduce a synergistic 2-butanone/water dopant system. This dual strategy enables the efficient conversion of (C 4 H 8 O) 2 H + to (H 2 O) n H + at ambient temperature. The resulting reagent ion, possessing a lower proton affinity, emerged as the predominant species. As a result, the NH 3 LOD is significantly lowered to 0.47 ppb, an improvement in sensitivity by approximately an order of magnitude. It exhibits superior stability, robust...