Monitoring SO sub(2) with Passive Samplers: A Laboratory Evaluation of Na sub(2)CO sub(3) and Triethanolamine as Absorbing Media

Short- and long-term passive sampling of sulfur dioxide was investigated with a badge and tube sampler, respectively. Both samplers used a filter of quartz fiber coated with sodium carbonate as a sampling layer. The sulfite is collected, and converted to the sulfate for measurement. For SO sub(2) concentrations ranging from 20 to 400 ppb, calibration tests showed linear uptake. Under a range of ambient conditions, the method was shown to have adequate capacity and sensitivity. After one week of exposure, detection limits were 34 and 4 mu g/m super(3), for the tube and badge sampler, respectively, and precision for both samplers ranged from 5 to 10%. When triethanolamine was substituted for the sodium carbonate substrate, the collection efficiency of the samplers was up to three times more dependent on relative humidity. Badge and tube samplers gave acceptable results at wind speeds greater than and less than 1 m/s, respectively. When the method was compared in the field to a diffusion denuder method, the results from the two methods were in good agreement.