Development of a respiratory circuit for high sensitive mass spectrometry and its clinical application

心肺运动试验在运动医学领域有着广泛的应用。在评价运动能力的指标中，无氧阈值是最重要的参数之一，但也不容易确定。另一方面，几项使用气相色谱法的研究报告称，人类呼出的空气中含有300多种低质量的未知物质。为了探索运动中可能与无氧代谢有关的化合物，我们开发了一种清洁空气回路系统，可用于高灵敏度的大气压电离质谱仪（APIMS）。我们在呼出的空气中检测不到乳酸。然而，我们观察到运动导致60个质量数或更多的离子强度增加。这一发现表明，在运动过程中，呼出的空气中仍有可能存在与无氧阈值相关的未知化学物质。从皮肤表面释放的化学物质尚不清楚，可能是因为尚未建立适当的采样方法来检测皮肤气体的低水平。大气压电离质谱仪（APIMS）可以检测到非常低水平的气体化合物。清洁气体捕集系统和APIMS的结合使用具有检测体内低水平代谢物的潜力。在本研究中，我们开发了一种新的气体捕获系统，用于分析可能含有多种挥发性化合物的皮肤气体。所开发的系统主要由质量流量控制器、气体清洁器和一个热控室组成，清洗后的气体通过该室。热传感器安装在腔室和连接管的表面，它们被加热器包围。皮肤表面完全被弯曲覆盖。在保持一定混合比的情况下，将蒙皮气用相同的载气稀释后引入APIMS。使用APIMS的正负电荷模式分析手掌皮肤气体的质谱。在两种电离状态下，光谱都得到了很好的再现。接下来，我们将皮肤气体的质谱与同一健康受试者呼出的空气的质谱进行了比较。皮肤气体的离子强度与呼出空气之间存在显著的线性关系。综上所述，开发了一种新型的高灵敏度APIMS气体捕集系统。该系统成功地检测了从皮肤中释放的多种低质量的挥发性化合物。少

Cardiopulmonary exercise testing is widely used in the filed of sports medicine. Among the indices for the evaluation of exercise capacity, anaerobic threshold is one of the most important parameters, which is, however, not easy to determine. On the other hands, several studies using gas-chromatography reported that exhaled air in humans contained more than 300 unknown substances with low mass numbers. To explore the chemical compounds that may be related to anaerobic metabolism during exercise, we therefore developed a clean air-circuit system that was available for atmospheric pressure ionization mass spectrometer (APIMS) with high sensitivity. We could not detect lactic acid in exhaled air. However, we observed that exercise caused increases in the ion intensities of 60 mass numbers, or more. This finding suggests that there still remains possibility to exist unknown chemicals in the exhaled air associated with the anaerobic thresholds during exercise.Chemical compounds released fro … More m the surface of the skin are not well known, possibly because appropriate sampling methods to detect the low levels of the skin gas have not been established. 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 that may contain numerous kinds 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 wee 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 camber. 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. Less