PASSIVE OZONE OXIDANT SAMPLER WITH COULOMETRIC DETERMINATION USING I2/NYLON-6 CHARGE-TRANSFER COMPLEX

A new passive sampler for ozone/oxidants and its simple analytical system have been developed. The sampler consists of a carbon paper collector coated with nylon-6 polymer and potassium iodide, several layers of membrane filters to remove interferences, and a spacer and Teflon meshes to control sampling rate. Iodine liberated by an oxidation reaction of KI with ozone is stabilized by forming a charge-transfer complex with nylon-6 and is accumulated in the nylon-6 layer. The amount of I2 is determined by constant-current coulometry using the collector as a positive electrode and a zinc plate as a counter electrode. This procedure is simple, requiring no pretreatment. The sampler was applicable for measurement of 6-8-h average personal exposures to ozone/oxidants. The effects of surface wind velocity, temperature, and humidity were small. However, with relative humidities below 20%, it would underestimate the ozone/oxidant concentration.