Patients with asthma exhale high concentrations of nitric oxide (NO), making the measurement of NO clinically important. Although we previously developed a 2-phenyl-4,4,5,5-tetramethylimidazoline-3-oxide-1-oxyl (PTIO) chip that relied on the reaction between NO gas and PTIO in the chip, the sensitivity and accuracy were insufficient for measuring NO in air exhaled by asthma patients. In this study, we focus on the conversion of NO to NO₂ in the reaction with PTIO, and devise a new method to measure the converted NO₂ using our previously developed NO₂ analytical chip. NO is converted to NO₂ in the PTIO chip and immediately released upon exposure to the atmosphere. This released NO₂ is trapped on the adjacent NO₂ analytical chip and reacts with diazo-coupling reagents to form an azo dye; a linear relationship was identified between the NO concentration and the change in absorbance at 525 nm due to production of the azo dye. The NO concentration could be measured in the 0−142 ppb range with a maximum error of ± 10 ppb at 142 ppb using the devised method, demonstrating sufficient sensitivity and accuracy for measuring NO in exhaled air. Furthermore, we successfully measured NO in the exhaled air of seven healthy adults, and detected ~19 ppb of NO, thus illustrating its feasibility for clinical use.

哮喘患者呼出高浓度的一氧化氮（NO），因此对NO的测量在临床上很重要。尽管我们之前曾开发过依赖于NO气体与PTIO之间反应的2-苯基-4,4,5,5-四甲基咪唑啉-3-氧化物-1-氧基（PTIO）芯片，但是灵敏度和准确性仍不足用于测量哮喘患者呼出的空气中的NO。在这项研究中，我们着重于与PTIO反应中NO转化为NO ₂的问题，并设计了一种使用我们以前开发的NO ₂分析芯片测量转化的NO ₂的新方法。NO在PTIO芯片中转换为NO ₂，并在暴露于大气中后立即释放。这发布了NO ₂被捕获在相邻的NO ₂分析芯片上，并与重氮偶合试剂反应形成偶氮染料。在NO浓度和由于偶氮染料的产生而在525nm处的吸光度变化之间发现线性关系。使用所设计的方法，可以在0-142 ppb范围内测量NO浓度，在142 ppb处最大误差为±10 ppb，证明了用于测量呼出空气中NO的足够的灵敏度和准确性。此外，我们成功地测量了七名健康成年人的呼出气中的NO，并检测到〜19 ppb NO，从而说明了其在临床上的可行性。