RESUMO
Based on the modification of inlet of a proton transfer reaction time of flight mass spectrometry ( PTR-TOF-MS) instrument developed in our laboratory, a new method for real-time and on-line quantitation of volatile organic compounds ( VOCs) from human exhalation was established. A 28-day real-time and on-line monitoring of exhaled breath from 23 volunteers (11 male healthy subjects, 11 female healthy subjects and 1 stomach-sick patient) was carried out and the experimental results showed that the major potential VOCs markers were identified as formaldehyde, propylene, acetone, acetaldehyde, isopropanol and isoprene, and their concentrations obeyed the Normal Distribution. The concentrations of formaldehyde, propylene and isopropanol were mainly in the range of 40 to 100 ppb, acetaldehyde in the range of 80 to 180 ppb, acetone in the range of 500 to 1500 ppb, and isoprene in the range of 8 to 20 ppb. Meanwhile, the concentrations for some compounds were different for men and women. Men have higher level of acetone, and women have higher levels of acetaldehyde and isopropanol. In addition, the concentrations of formaldehyde and acetone in the exhaled breath of stomach sicknesses were significantly higher than that in healthy people. Ethanol and acetaldehyde were the main potential markers of exhale breath after drinking alcohol. The acetaldehyde was the major metabolite of ethanol, and the concentration of acetaldehyde changed with the concentration variation of ethanol in degradation process.