Trends in Atmospheric Trace Gas Measurement Instruments with Membrane-based Gas Diffusion Scrubbers

摘要

A diffusion scrubber (DS) is an excellent tool for gas analysis, and there are many types of DS devices, varying both in structure and construction. In this paper, recent work on atmospheric trace gas measurement by means of DS devices are reviewed. Theoretical considerations on representative DSs are summarized first. Then, characteristics of the key material, a gas diffusion membrane, are discussed, and recent improvements and novel scrubbers for highly effective collection are outlined. A chromatograph is a suitable tool for multi-gas analysis of the collected species. On the other hand, solid state fluorescence/absorbance detectors have been developed for the continuous measurement of target gases. The methods based on the DS collection and the subsequent detection have high sensitivities, and the detection limits can be in the low pptv levels. Accordingly, they are capable of measuring background levels, and detecting very low levels of contaminants in a cleanroom. Miniaturized advanced DS units, perhaps the next generation of DS devices are introduced at the end of this review. DS systems have significantly contributed to the our knowledge of atmospheric dynamics and atmospheric chemistry.