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 CHBr reactant ion and ethylene molecule was discovered and studied for the first time. The formation of readily identifiable [CHBr·CH] 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 CHBr 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.

中文翻译：

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一种新型光电离诱导取代反应化学电离飞行时间质谱法，用于高灵敏度检测痕量呼出乙烯


高灵敏度和快速检测乙烯这种对人体生理代谢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），用于微量呼出乙烯检测。首次发现并研究了涉及 CHBr 反应物离子和乙烯分子之间的取代反应的有趣电离现象。易于识别的[CHBr·CH]子离子的形成极大地提高了乙烯的电离效率，使得信号强度比单光子电离模式提高了约800倍。对CHBr反应物离子强度和离子-分子反应时间进行了优化，并采用Nafion管消除湿度对乙烯电离的影响。因此，在 100% 相对湿度下，乙烯的检测限 (LOD) 在 30 秒内达到低至 0.1 ppbv。 PSCI-TOFMS应用于快速检测健康吸烟者和非吸烟者呼出的微量乙烯，证明了该系统在临床诊断、大气测量和过程监测中痕量乙烯测量的令人满意的性能和潜力。