Abstract：
Highly sensitive and rapid detection of ethylene, the smallest alkene of great significance in human physiological metabolism remains a great challenge. In this study, we developed a new photoionization-induced substitution reaction chemical ionization time-of-flight mass spectrometry (PSCI-TOFMS) for trace exhaled ethylene detection. An intriguing ionization phenomenon involving a substitution reaction between the CH2Br2+ reactant ion and ethylene molecule was discovered and studied for the first time. The formation of readily identifiable [CH2Br·C2H4]+ product ion greatly enhanced the ionization efficiency of ethylene, which led to approximately 800-fold improvement of signal intensity over that in single photon ionization mode. The CH2Br2+ reactant ion intensity and ion-molecule reaction time were optimized, and a Nafion tube was employed to eliminate the influence of humidity on the ionization of ethylene. Consequently, a limit of detection (LOD) as low as 0.1 ppbv for ethylene was attained within 30 s at 100 % relative humidity. The application of PSCI-TOFMS on the rapid detection of trace amounts of exhaled ethylene from healthy smoker and non-smoker volunteers demonstrated the satisfactory performance and potential of this system for trace ethylene measurement in clinical diagnosis, atmospheric measurement, and process monitoring.
摘要：
乙烯的高灵敏度和快速检测，在人体生理代谢中具有重要意义的最小烯烃仍然是一个巨大的挑战。在这项研究中,我们开发了一种新的光电离诱导取代反应化学电离飞行时间质谱（PSCI-TOFMS），用于痕量呼出气乙烯检测。首次发现并研究了一种有趣的电离现象，该现象涉及CH2Br2反应物离子与乙烯分子之间的取代反应。容易识别的[CH2Br·C2H4]产物离子的形成大大提高了乙烯的电离效率，与单光子电离模式相比，信号强度提高了约800倍。优化了CH2Br2+反应物的离子强度和离子分子反应时间,采用Nafion管来消除湿度对乙烯电离的影响。因此,在100％相对湿度的30s内，乙烯的检测限（LOD）低至0.1ppbv。PSCI-TOFMS在快速检测健康吸烟者和非吸烟者志愿者呼出痕量乙烯中的应用证明了该系统在临床诊断中用于痕量乙烯测量的令人满意的性能和潜力。大气测量,和过程监控。
