Chemiluminescence Determination of Sulphite Using a Cyclometalated Iridium Complex As Chemiluminescence Reagent

A simple, fast and accurate chemiluminescence (CL) method for the determination of sulphite has been developed, based on its sensitizing effect on the CL reaction between a novel water-soluble iridium complex, [(dpci)2Ir(bvbbi)](PF6) (dpci =  3,4-diphenylcinnoline; bvbbi =  N,N'-bivinylester-(1)H,(1')H-[2,2'] bibenzimidazole) and cerium(IV). Under the optimal experimental conditions, the increased CL response was linear, with the concentration of sulphite over the range 5.0 × 10(-7)-5.0 × 10(-4)  mol/L. The detection limit of the method was 1.6 × 10(-7)  mol/L, with a relative standard deviation (RSD) of 2.7% for nine repetitive determination of 1.0 × 10(-4)  mol/L sulphite. The method was successfully applied to the quantitative analysis of sulphite in sugar samples. The possible reaction mechanism of sulphite on the [(dpci)2Ir(bvbbi)](PF6)-cerium(IV) system is also briefly discussed.