Determination of chlorine dioxide using 4-aminoantipyrine and phenol by flow injection analysis

The determination of chlorine dioxide (ClO2) using 4-aminoantipyrine (4-AA) and phenol by flow injection analysis, was investigated in the presence of various chlorinated species that can occur under normal water-treatment conditions. The colorimetric method with 4-AA and phenol relies on the use of a Tris-HCl buffer. Adjusting the reagent to pH 9.0 with the Tris-HCl buffer gives high sensitivity and is effective in eliminating hypochlorite interference. Furthermore, using purge trap system for pretreatment makes it possible for this method to eliminate interferences from metal ions, as well as other oxychlorinated compounds, such as chlorite and chlorate.