中文摘要：

利用自主研制的高灵敏呼气检测质子转移反应质谱（ PTR-MS），对一名口臭受试者的口腔吹出气体、鼻子呼出气体和口腔内气体分别进行多组分实时监测，发现了该受试者呼气中3种引起口臭的挥发性硫化物（ VSCs）的来源并不相同，其中甲硫醇主要来源于口腔，硫化氢和二甲基硫则主要来源于肺或呼吸道。本研究不仅发现了口腔内气体在PTR-MS呼气监测过程中的特征变化趋势，还分析了呼出气体中3种VSCs的来源，对于呼气的正确采样和检测具有重要的指导意义。

英文摘要：

To develop a kind of noninvasive method of breath diagnosis in diseases, much attention has been paid to the study of the relation between diseases and volatile organic compounds in human breath gas. However, the gas in oral cavity was usually ignored in many studies of breath gas. The bad breath odor of a participant was studied by a home-made proton transfer reaction mass spectrometer（ PTR-MS） . The breath via the mouth, breath via the nose and the air in the mouth cavity were monitored with the mode of multiple ion detect scans. The results show that three different volatile sulfur compounds that cause bad breath odor should be attributed to different sources. The source of methyl mercaptan in breath is oral cavity, and the source of hydrogen sulphide and dimethylsulfide in breath is lung or respiratory tract. The related result is very important to sampling and detection of breath gas.