化学
离子源
气体分析呼吸
电离
质谱法
分析化学(期刊)
环境电离
离子
大气压化学电离
飞行时间质谱
化学电离
放电电离检测器
色谱法
有机化学
作者
Yan Wang,Jichun Jiang,Hua Lee,Keyong Hou,Yuanyuan Xie,Ping Chen,Wei Liu,Qingyun Li,Shuang Wang,Haiyang Li
标识
DOI:10.1021/acs.analchem.6b01707
摘要
Photon ionization mass spectrometry (PI-MS) is a widely used technique for the online detection of trace substances in complex matrices. In this work, a new high-pressure photon ionization (HPPI) ion source based on a vacuum ultraviolet (VUV) Kr lamp was developed for time-of-flight mass spectrometry (TOFMS). The detection sensitivity was improved by elevating the ion source pressure to about 700 Pa. A radio frequency (RF)-only quadrupole was employed as the ion guide system following the HPPI source to achieve high ion transmission efficiency. In-source collision induced dissociation (CID) was conducted for accurate chemical identification by varying the voltage between the ion source and the ion guide. The high humidity of the breath air can promote the detection of some compounds with higher ionization potentials (IPs) that could not be well detected by single photon ionization (SPI) at low pressure. Under 100% relative humidity (37 °C), the limits of detection down to 0.015 ppbv (parts per billion by volume) for aliphatic and aromatic hydrocarbons were obtained. This HPPI-TOFMS system was preliminarily applied for online investigations of the exhaled breath from both healthy nonsmoker and smoker subjects, demonstrating its analytical capacity for complicated gases analysis. Subsequently, several frequently reported VOCs in the breath of healthy volunteers, i.e., acetone, isoprene, 2-butanone, ethanol, acetic acid, and isopropanol, were successfully identified and quantified.
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