A high-efficiency annular diffusion scrubber for the collection of water-soluble trace atmospheric gases

The design and construction details of an annular diffusion scrubber to be used as a quantitative gas sampler are described. A large-diameter inner tube (12 mm o.d.) wrapped with liquid channel interior of thin membrane (70 micro m thickness) provided high collection efficiency. With SO2 as the test gas, the performance data for a high-efficiency annular diffusion scrubber, coupled to an ion chromatograph, are presented. Quantitative collection and excellent reproducibility are observed at air sampling rates up to 2 L/min. The estimated detection limit is 4 pptv for a 20-L air sampling volume.