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A diffusion scrubber, employing a porous fluorocarbon membrane as the sampling tube and with a scrubber solution flowing into a narrow annular space exterior to the membrane, is described. The use of this diffusion scrubber with a dilute buffered formaldehyde solution as the scrubber solution has been exploited for collecting sulphur dioxide. Collection efficiencies are reported for sampling rates of up to 3 I min-1. The response time to a SO2 input pulse in the continuous analysis mode is demonstrated using dilute hydrogen peroxide as the scrubber solution and a conductivity detector. The advantages of a diffusion scrubber for collecting atmospheric gases are discussed. A simple inexpensive design of permeation tubes for standard gas sources is also reported.

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