Abstract
Performance of a diffusion sampler was evaluated for formaldehyde (HCHO) gases in a small chamber with a constant gas generation system under controlled meteorological conditions (temperature, humidity and wind speed) . The sampler consists of porous polyolefin tube uniformly packed with DNPH coated silica gel as collection media. The relative standard deviation for triplicate analysis of the amount of HCHO collected by this sampler was 4.5 % for 50 ppb. The linear relationship was found between amounts of HCHO collected and exposure time under constant conditions. The humidity and wind velocity have no influence on the collection efficiency of the sampler. And the conversion rate did not show apparent temperature dependence. This method was applied to a preliminary field test in a newly built house. The results showed that 47-51 ppb of HCHO was determined in indoor air as 24h-averaged concentration and agreed to those by active sampling method.
