[Method for multiple gaseous pollutants monitoring by passive sampler]

A new monitoring method used passive samplers by molecular diffusion was developed to determine simultaneously the concentration of HCHO, NO2 and SO2 in the air. Pretreated activated-charcoal fibers were used as absorbent layer. After being sampled, the gaseous pollutants collected in absorbent layer were desorbed by 0.05 mol/lNaOH solution and oxidized by 0.3% H2O2 to HCOO-, NO2- and SO4(2-), finally were analyzed using ion chromatographic techniques. The passive sampler can be used in the condition of face velocity of 0.2-1.5 m/s, temperature of -10-35 degrees C and relative humidity of 20%-80%. The sample rates for HCHO, NO2 and SO2 are 67 ml/min, 80 ml/min and 64 ml/min, respectively. The relative standard deviations are 7.3%, 3.6% and 6.8%. The lowest quantitative detection concentrations of 24 h sampling for HCHO, NO2 and SO2 are 0.026 mg/m3, 0.008 mg/m3 and 0.023 mg/m3 respectively. In field comparative test with active sample method, the new method show that its relative overall uncertainty for HCHO, NO2 and SO2 are 23%, 23% and 18%. By the method, sampling and analyzing three kinds of gaseous pollutants simultaneously can be realized, and the foreground of application of diffusive sampling technology can be expanded.