The fluorescent reaction of the reagent glyoxal-bis-(2-hydroxyanil) (GBHA) with cadmium was studied. Based on this chelation reaction, a sensitive, rapid, direct spectrofluorimetric method for the determination of trace cadmium with GBHA has been developed. The reaction conditions for the fluorescence system of cadmium with GBHA were established. The cadmium ion can form a stable chelate with GBHA, having a ratio of 1:3 in the 12.0 -13.0 pH range. The maximum excitation and emission wavelengths are 227.4 nm and 320.0 nm for the cadmium chelate, respectively. The fluorescence intensity of the cadmium chelate remains stable from 20 to 150 min. Under the optimal experimental conditions the fluorescence intensity is a linear function of concentration in the range 1.0-10.0 ng mL-1 of cadmium and the detection limit is 0.65 ng mL-1 of cadmium. Interferences of foreign ions were studied. The method has been successfully applied to the determination of cadmium in the sewage.
glyoxal-bis-(2-hydroxyanil); cadmium; spectrofluorimetry
