Technical Bulletin No. 0520: Optimization and Evaluation of an Impinger Capture Method for Measuring Chlorine and Chlorine Dioxide in Pulp Bleach Plant Vents

This report describes results of an NCASI study of an impinge capture dual pH potassium iodide method for measuring chlorine and chlorine dioxide in bleach plant vent gases. Although the technique is in wide use for this purpose, its performance apparently has never been evaluated. This study showed that pH buffering of the capture solution was necessary to avoid the formation of falsely high chlorine levels; other features of the performance of the method were evaluated, and a method for removing a sulfur dioxide interference was developed.