| Abstract: | The principle of this detector is based on the measurement of the intensity of the ultraviolet fluorescence of SO2 produced by absorption of the Zn 2138 Å or Cd 2288 Å line. The fluorescence intensity was found to be linear from 0.1 to 500 ppm of SO2 in air with the Zn lamp and from 0.1 to 1600 ppm with the Cd lamp. The detection limit at present is about 20 ppb. There is no detectable interference from O3, H2S, NO2, CO2, CO, or H2, although the presence of a large concentration of CS2 (500 times as much as SO2) NO (500 times) or C2H4 (4000 times) interferes with the measurement. The presence of 2% H20 reduces the signal by 25%, while up to 1 % CH4 has almost no effect. |
