****!!!!****!!!!**** (1991) {Is this back-up method? Or actually fully validated?} "Collection devide: An air sample is collected using a calibrated sampling pump and a midget fritted glass bubbler. The bubbler contains a collection solution of 0.02% potassium iodide (KI) in a sodium carbonate/sodium bicarbonate buffer." "Analytical Procedure: In the weakly basic solution, chlorine dioxide reacts with KI to form chlorite (ClO2¯) which is then determined by an ion chromatograph equipped with a conductivity detector and gradient pump." "The stock standard should be standardized at least monthly. It was noted during testing that this standard solution decreases in concentration approximately 4% per month. No significant difference in results was noted when sampling at different humidities. As shown in the mixture study, Cl2 does not interfere with the sampling or ion chromatographic analysis of ClO2 at the concentrations tested. Although a resultant 10% decrease in ClO2 and 7% increase in Cl2 concentrations occurred, this could have been due to the difficulty in generating both gases simultaneously. A mixture of ClO2 and Cl2 can be collected and analyzed together; however,Cl2 measurements are considered for screening purposes only. Further work is necessary to validate the KI/buffer sampling and IC analysis for Cl2.Detection limits are adequate if samples are taken for 240 min at 0.5 L/min"