Determination of active chlorine in air by bonded phase sorbent collectionand spectrophotometric analysis

The development and application of a collection method for total combined g as-phase active chlorine (i.e., Cl-2, HOCl and chloramines) based on a sulf onamide-functionalized silica gel sorbent are presented. Preparation method s for the sorbent are described, as are procedures for chemical and physica l characterization, such as chlorine capacity and chlorine collection effic iency. For determination of the collected chlorine, a modified version of t he N,N'-diethyl-p-phenylenediamine (DPD) colorimetric method was employed, which yielded a detection limit of 0.1 mu g of chlorine. At flow rates rang ing from 31 to 294 ml min(-1), the collection efficiency was > 90% based on breakthrough analysis. Recovery of chlorine spikes from 0.05 g aliquots of the sorbent was not quantitative (similar to 60%) but was reproducible; th e recovery is accounted for in samples by adding weighed amounts of sorbent to the standards. Analytical data for active chlorine concentrations (i.e. , Cl-2 + HOCl) above a swimming pool are presented.