On-line Detection of Volatile Sulfur Compounds in Breath Gas by Proton Transfer Reaction Mass Spectrometry

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.