Usefulness of APIMS for monitoring of nitrogen dioxides during NO inhaling therapy

该项目是为了在一氧化氮吸入治疗过程中直接测量二氧化氮。本研究采用大气压电离质谱仪(APIMS)。首先，我们通过改变探测器和第一电离室和第二电离室之间的狭缝尺寸来改进APIMS原型。然后研究了电离气体和样品载气的组合。我们找到了在Ar中SF6作为电离气体，Ar作为样品载气测定NO2的良好组合。成功地获得了常规化学发光法检测不到的NO中NO2的校正曲线。应用化学发光分析仪和该系统对纯气中杂质气体的吸收塔质量进行了评价。分子筛是脱除NO中NO2的最佳吸收剂。另外，如果在进入患者之前使用SODALIME作为吸收器，我们注意到肯定需要良好的过滤器(过滤器可能产生任何杂质)才能去除微小的颗粒物或多种杂质，因为APIMS在光谱图中显示了许多不规则的峰。在野百合碱诱导的大鼠肺动脉高压模型动物吸入NO治疗过程中，加入浓度小于1%的氮氧化物。该动物模型对NO治疗本身不敏感，不能看到不同浓度的二氧化氮在较长时间内对NO的影响。应该尝试其他模拟肺动脉高压的方法，如低氧，并且必须能够对动物的情况进行更长时间的观察，最长可达几个小时。

This project was conducted for measuring directly nitrogen dioxide during nitric oxide inhaling therapy. An Atmospheric Pressure Ionization Mass Spectrometry (APIMS) device was utilized in this study. First we improved the prototype of APIMS by changing the detector and the slit sizes between the first ionization room and the second ionization room. Then combinations of ionization gas and sample carrier gas were investigated. We found the good combination of SF6 in Ar for ionization gas and Ar for sample carrier gas for determining NO2. Calibration curve of NO2 in NO was obtained successfully, which was impossible by conventional chemiluminescence method detectors. Chemiluminescence analyzer and this system was applied for evaluation of the quality of absorber of impurity gases in pure gas. Molecular Sieve was the best absorber for removal of NO2 in NO.Moreover if SODALIME was used for absorber before entering into the patient, we noticed that the definite necessity of good filter (filter may produce any impurities) in order to remove small particulate matter or many kinds of impurities, because of APIMS showed many irregular peaks in the spectrogram. Then we applied nitrogen oxides in the concentration of less than 1 % of nitric oxide during NO inhaling therapy for model animals of pulmonary hypertension by monocrotaline. This animal model was not so sensitive for NO therapy itself that we could not see effects of varied concentration of nitrogen dioxides in NO for longer duration of therapy. Other methods for mimic pulmonary hypertension such as hypoxia should be tried and longer period observation of the conditions of animals up to several hours must be enabled.