Pneumatoamperometric determination of various oxidants and total dissolved chlorine

Trace levels of dissolved nitrite, chromate, permanganate, cerium(IV), bromate, chlorine and bromine are treated with iodide to produce iodine, which is then determined pneumatoamperometrically, i.e., by purging it from solution with nitrogen and quantifying it at a gold, gas-porous electrode by electro-oxidation to iodate. All the dissolved oxidants produce linear calibration curves. Detection limits range from 30 to 60 ppb. Aqueous sample sizes of 4 ml are used.