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

该项目的主要目标是设计、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：硫化氢、二氧化硫、羰基硫化物、二硫化碳和二甲基硫化物的超痕量气体标准。尽管这些硫物种对大气具有重要意义，但用于它们分析的不同分析方法的测量等价性往往是未知的。因此，科学界正在制定一个相互比较项目来解决这一问题。在总体比对项目的这一初始阶段建立的中央校准系统将提供获取各种分析技术的性能特征所需的参考气体标准。该校准系统将包括一个三级动态稀释装置，其中包含一个无硫零稀释空气源，一个全特氟龙流动网络，作为每种含硫气体来源的压缩气瓶，用于精确调节所有气体流量的电子质量流量控制器，以及单独的进样系统，用于引入潜在的基质干扰。校准系统制备的硫磺气体标准浓度范围为950pptv至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%.//