Flow injection chemiluminescence determination of sulphite

Abstract

A comparison is made of the use of riboflavin and 3-cyclohexylaminopropanesulphonic acid (CAPS) to increase the sensitivity of the determination of sulphite in a flow injection procedure based on the chemiluminescence produced by permanganate oxidation in an acidic solution. Both procedures give linear calibration graphs for 5–60 ng of sulphite, but the CAPS procedure has a lower detection limit (1.2 ng) and better relative standard deviation (RSD)(2.5% for 40 ng, n=10). Riboflavin enhancement arises from energy transfer, but the reason for the CAPS enhancement could not be identified with certainty.