Methods Development for Sampling and Analysis of Chlorine, Chlorine Dioxide, Bromine, and Iodine (Project 4558-R1)

摘要

This report describes an unsuccessful attempt to develop a personal air sampling and analysis method for the determination of chlorine dioxide in workplace air. To take advantage of the relatively high inherent reactivity of chlorine dioxide, candidate reactive solids were screened for their potential utility as sampling media. In contrast to chlorine dioxide's well-known solution reactivity, however, its reactivity in the gas phase with solid sorbents was found to be rather poor and to be confined largely to the formation of ionic salts or complexes. Hence, no suitable solid-state sampling medium was found. An impinger-type spectrophotometric method based on the decolorization of chlorophenol red (CPR) by chlorine dioxide was then investigated. The precision, sampling capacity, storability, specificity, sensitivity, and analyte slippage rates associated with this method appeared to be quite acceptable for validation, but the accuracy of the method could not be established within the remaining contract budget and period of performance. The method exhibited a systematic bias relative to the reference method, which was based on dual-pH iodometry, and our attempts to determine which method was at fault were not successful.