Development and Deployment of Atmospheric Pressure Ionization Mass Spectrometer for Determining SO2, DMS, DMSO, and DMSO2 on Aircraft and Ship Platforms

小行星9617362 本研究的目的是开发和测试仪器，用于确定二甲硫醚（DMS），二甲亚砜（DMSO），二甲基砜（DMSO 2），二氧化硫（SO2）的检测下限为1万亿分之一的体积（pptv），信噪比为3，采样频率为每秒1。 所采用的方法将基于大气压电离四极杆质谱法。 已在实验室中演示了DMS、DMSO和DMSO 2的正离子APIMS和SO 2的负离子APIMS。 APIMS仪器将基于Extrel质谱四极杆系统，该系统在研究人员以前的项目中已现场使用多年。 这些APIMS仪器的准确度和精确度将通过使用同位素标记的分析物变体作为内部标准而大大提高，这些内部标准在过去使用同位素标记标准的气相色谱-质谱法（GC/MS/ILS）进行部署。 使用这种方法，仪器的精密度和准确度独立于仪器灵敏度和其他因素，如采样中的分析物损失。 此外，由于标准品的信号可用于每个样品，并且标准品的浓度是已知的，因此可以精确计算每个样品的仪器灵敏度和检测下限。 为了验证这一新的现场测量环境空气中这些硫化合物的仪器方法，APIMS仪器将与现有的GC/MS/ILS仪器进行相互比较，后者是NASA-CITE-3和NSF-GASIE评估的一部分。 为了最大限度地减少拟议工作的成本，现有的质谱仪将用于建立和部署APIMS进行现场测试。 这将需要对实验室仪器进行一些修改，以达到安全和操作的适航标准。 最终目标是实现测量时间比Curr ent GC/MS技术快200-4000倍，这套硫化物。 这些新仪器将更小，更轻，并且在高空飞行器使用时消耗更低的功率。 如果使用单四极APIMS进行的初始现场测试表明干扰显著，则将使用三重四极质谱仪进一步评价离子化学，以确定所需的分析物特异性。 在成功测试APIMS对这些硫化合物进行初步实地测量之后，将开发APIMS，用于在二甲硫醚含量较高的区域对二甲硫醚通量进行涡动相关测量。

9617362 Bandy The objectives of this study are to develop and test instrumentation for determining dimethyl sulfide (DMS), dimethyl sulfoxide (DMSO), dimethyl sulfone (DMSO2), and sulfur dioxide (SO2) with a lower limit of detection of 1 part-per-trillion-by-volume (pptv) with a signal to noise ratio of 3 at a sample frequency of 1 per second. The approach to be employed will be based on atmospheric pressure ionization quadrupole mass spectrometry (APIMS). Positive ion APIMS for DMS, DMSO, and DMSO2 and negative ion APIMS for SO2 have been demonstrated in the laboratory. The APIMS instruments will be based on Extrel Mass Spectrometry quadrupole systems, which have many years of field use in the investigator's previous projects. The accuracy and precision of these APIMS instruments will be substantially enhanced by using isotopically labelled variants of the analytes as internal standards that have been deployed in the past using gas chromatography - mass spectrometry with isotopically labelled standards (GC/MS/ILS). Using this approach the precision and accuracy of the instrument are independent of the instrument sensitivity and other factors, such as, analyte loss in sampling. Furthermore, because the signal from the standard is available for each sample and the concentration of the standard is known, the instrument sensitivity and lower limit of detection can be precisely computed for each sample. To validate this new instrumental approach for field measurements of these sulfur compounds in ambient air, the APIMS instruments will be intercompared to an existing GC/MS/ILS instrument, which was a part of the NASA-CITE-3 and NSF-GASIE evaluations. To minimize the cost of the proposed work the mass spectrometers on hand will be used to build and deploy the APIMS for field tests. This will require some modification to laboratory instruments to attain airworthiness standards in safety and operation. The end goal is to achieve measurement times 200-4000 times faster than the curr ent GC/MS techniques for this suite of sulfur compounds. These new instruments will be much smaller, lighter, and consume lower power for high altitude aircraft use. If initial field tests with the single quad APIMS indicate that interferences are significant, a triple quadrupole mass spectrometer will be employed to further evaluate the ion chemistry for the required analyte specificity. Successful tests of the APIMS for initial field measurements of these sulfur compounds will be followed by development of an APIMS for eddy correlation measurements of DMS fluxes in regions where significant DMS levels occur.