Construction and Performance Verification of a Multi-Stage Standardization System for Sulfur Gases

本课题的主要目标是设计、构建和验证一个可靠的校准系统，用于制备五种含硫化合物的超微量气体标准品；硫化氢，二氧化硫，羰基硫化氢，二硫化碳和二甲基硫化氢。虽然这些硫化物在大气中具有重要意义，但用于分析它们的不同分析方法的测量等效性往往是未知的。因此，科学界正在制定一个相互比较项目来解决这个问题。在整个比对项目的初始阶段建立的中央校准系统将提供所需的参考气体标准，以获取各种分析技术的性能特征。该校准系统将由三级动态稀释装置组成，该装置包含无硫零稀释空气源，全聚四氟乙烯流动网络，压缩气瓶作为每种硫气体的来源，用于精确调节所有气体流量的电子质量流量控制器，和单独的进气系统，以引入潜在的矩阵干扰。校准系统制备的硫气体标准浓度范围从950 pptv到12pptv，最大不确定度小于7%。//

The primary goal of this project is to design, construct, and validate a reliable calibration system for preparing ultra- trace gas standards for five sulfur-containing compounds; hydrogen sulfide, sulfur dioxide, carbonyl sulfide, carbon disulfide, and dimethylsulfide. Although these sulfur species are of major atmospheric importance, the measurement equivalency of the different analytical methods used for their analysis is often unknown. Consequently, an intercomparison project is being developed by the scientific community to address this issue. The central calibration system built during this initial phase of the overall intercomparison project will provide the reference gas standards required to access the performance characteristics of the various analytical techniques. This calibration system will consist of a three-stage dynamic dilution apparatus that contains a source of sulfur-free zero dilution air, an all-Teflon flow network, compressed gas cylinders as the source of each sulfur gas, electronic mass- flow controllers for the precise regulation of all gas flows, and separate inlet systems for the introduction of potential matrix interferences. Concentrations of the sulfur gas standards prepared by the calibration system will cover a range from 950 pptv to 12pptv and have a maximum uncertainty of less than 7%.//