Determination of Atmospheric Oxidants

The atmospheric oxidants that are commonly determined include ozone, hydrogen peroxide, organic peroxides, and chlorine. The classic manual method for the analysis of oxidants is based on their oxidation of I ion followed by spectrophotometric measurement of the product. The sample is collected in 1% KI buffered at pH 6.8. Oxidants react with r ion as shown by the following reaction of ozone  

The absorbance of the colored Ij product is measured spectrophotometrically at 352 nm. Generally, the level of oxidant is expressed in terms of ozone, although it should be noted that not all oxidants— peroxyacetyl nitrate (PAN), for example—react with the same efficiency as O3. 

The currently favored method for oxidant analysis uses the chemiluminescent reaction between ozone and ethylene. This reaction emits light at a maximum intensity of 435 nm. The intensity of emitted light is directly proportional to the level of ozone. 

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