Flow-injection inhibition chemiluminescence determination of indapamide based on luminol-ferricyanide reaction

A novel and sensitive chemiluminescence (CL) method for the determination of indapamide coupled with flow-injection analysis (FIA) technique is developed in this paper. It is based on the inhibition effect of the studied drug on the chemiluminescence emission of luminol-potassium ferricyanide system. Under the optimum conditions, the decreased CL intensity is proportional with the concentration of indapamide in the range of 1 x 10(-8) to 1.0 x 10(-6) g ml(-1). The detection limit is 3.4 x 10(-9) g ml(-1) (3sigma). A complete analysis could be performed in 45 s including washing and sampling, giving a throughout of about 90 h(-1). The relative standard deviation (R.S.D.) for 11 parallel measurements of 1.0 x 10(-7) g ml(-1) indapamide is 3.0%. The proposed method has been applied for the determination of indapamide in its pharmaceutical formulations. The results obtained compared well with those by an official method. The possible inhibition mechanism of indapamide on luminol-potassium ferricyanide CL system was discussed briefly.