DETERMINATION OF SILICATE BY ION-EXCLUSION CHROMATOGRAPHY WITH LUMINOL CHEMILUMINESCENCE DETECTION

An increased chemiluminescence (CL) emission was produced upon mixing an acidified solution of silicate with a basic solution of luminol and hydrogen peroxide. The new CL reaction was used to develop a simple and rapid post-column detection system for selective determination of silicate after separation by ion-exclusion chromatography (ICE). Separation of silicate from other anions like phosphate, nitrite, sulfide or carbonate ion was achieved using a low-capacity cation-exchange column and a dilute perchloric acid solution as an eluent. Also, the present method has an advantage of eliminating interferences from ionic metal species. The detection limit of 50 ng cm-3 and a linear calibration graph with a dynamic range from 100 ng cm-3 to 30 mug cm-3 was obtained for silicon(IV). The proposed ICE-CL method was applied to the determination of silicate in tap and river water samples.