Proton-transfer-reaction mass spectrometry (PTR-MS) is widely used in atmospheric sciences for measuring volatile organic compounds in real time. In the most widely used type of PTR-MS instruments, air is directly introduced into a chemical ionization reactor via an inlet capillary system. The reactor has a volumetric exchange time of ∼0.1 s, enabling PTR-MS analyzers to measure at a frequency of 10 Hz. The time response does, however, deteriorate if low-volatility analytes interact with surfaces in the inlet or in the instrument. Herein, we present the extended volatility range (EVR) PTR-MS instrument which mitigates this issue. In the EVR configuration, inlet capillaries are made of passivated stainless steel, and all wetted metal parts in the chemical ionization reactor are surface-passivated with a functionalized hydrogenated amorphous silicon coating. Heating the entire setup (up to 120 ^∘C) further improves the time-response performance.We carried out time-response performance tests on a set of 29 analytes having saturation mass concentrations C⁰ in the range between 10⁻³ and 10⁵ µg m⁻³. The $\mathrm{1}/e$-signal decay times after instant removal of the analyte from the sampling flow were between 0.2 and 90 s for gaseous analytes. We also tested the EVR PTR-MS instrument in combination with the chemical analysis of aerosols online (CHARON) particle inlet, and $\mathrm{1}/e$-signal decay times were in the range between 5 and 35 s for particulate analytes. We show on a set of example compounds that the time-response performance of the EVR PTR-MS instrument is comparable to that of the fastest flow tube chemical ionization mass spectrometers that are currently in use. The fast time response can be used for rapid (∼1 min equilibration time) switching between gas and particle measurements. The CHARON EVR PTR-MS instrument can thus be used for real-time monitoring of both gaseous and particulate organics in the atmosphere. Finally, we show that the CHARON EVR PTR-MS instrument also rapidly detects highly oxygenated species (with up to eight oxygen atoms) in particles formed by limonene ozonolysis.

中文翻译：

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引入扩展的挥发性范围质子转移反应质谱仪（EVR PTR-MS）

质子转移反应质谱法（PTR-MS）被广泛用于大气科学中以实时测量挥发性有机化合物。在最广泛使用的PTR-MS仪器中，空气是通过入口毛细管系统直接引入化学电离反应器中的。反应器的体积交换时间为〜0.1 s，使PTR-MS分析仪能够以10 Hz的频率进行测量。但是，如果低挥发性分析物与进样口或仪器中的表面相互作用，则时间响应会变差。本文中，我们介绍了扩展了波动率范围（EVR）的PTR-MS仪器，可缓解此问题。在EVR配置中，入口毛细管由钝化不锈钢制成，化学电离反应器中的所有湿润金属零件均被功能化的氢化非晶硅涂层表面钝化。加热整个装置（最高 ^120∘C）可进一步提高时间响应性能。我们对29种分析物进行了时间响应性能测试，饱和质量浓度C ⁰在10 ^-3之间和10 ⁵  µg m ^-3。这$\mathrm{1个}/Ë$对于气态分析物，从采样流中立即去除分析物后的信号衰减时间在0.2到90 s之间。我们还将EVR PTR-MS仪器与在线气雾剂（CHARON）颗粒入口的化学分析结合起来进行了测试，并且$\mathrm{1个}/Ë$对于颗粒分析物，信号衰减时间在5到35 s之间。我们在一组示例化合物上表明，EVR PTR-MS仪器的时间响应性能可与目前使用的最快流量管化学电离质谱仪相媲美。快速的时间响应可用于 气体和颗粒物测量之间的快速切换（约1分钟的平衡时间）。因此，CHARON EVR PTR-MS仪器可用于实时监测大气中的气态和颗粒有机物。最后，我们证明了CHARON EVR PTR-MS仪器还可以快速检测出柠檬烯臭氧分解形成的颗粒中的高氧物种（最多8个氧原子）。