Abstract
Atmospheric pressure ionization mass spectrometers (APIMS) can detect very low levels of gaseous compounds. The combined use of a clean gas-trap system and APIMS has the potential of detecting low levels of metabolites in the body. In the present study, we developed a new gas-trap system for the analysis of skin gas which may contain numerous kind of volatile compounds. The developed system consists mainly of mass-flow controllers, gas cleaners and a thermo-controlled chamber in which the cleaned gases pass. Heat sensors were attached to the surfaces of the chamber and connecting-tube, which were surrounded by a heater. The surface of the skin was completely covered with the chamber. While maintaining a constant mixing ratio, the skin gas was diluted with the same carrier gas and introduced into the APIMS. The mass spectrum of the skin gas from the palm was analyzed using both negative and positive charge modes of the APIMS. In both ionization states the spectrums were well reproduced. We next compared mass spectrums of the skin gas with those of exhaled air in the same healthy subjects. There was a significant linear relationship between ion intensities of skin gas and exhaled air. In conclusion, a new type of gas-trap system was developed for biological application of an APIMS with high sensitivity. The system successfully detected numerous kinds of volatile compounds with low mass numbers released from the skin. [Jpn J Physiol 54 Suppl:S113 (2004)]
