A simple, selective and sensitive spectrophotometric method was proposed to determine trace amounts of cadmium by reacting with four new azo dye reagents (L1-4) derived from 2–amino-3-hydroxypyridine to give red colored complexes with high molar absorptivity 6.26, 4.26, 2.32, 10.52 (x104 L mol-1 cm-1) and Sandell's sensitivity of 0.0017, 0.0026, 0.0048, 0.0010 µg cm-2 for (L1, L2, L3, L4), respectively. The effective parameters on complex formation such as pH, concentration of chelating agent, sequence of addition, time and temperature were optimized. The analytical characteristics of the method such as detection and quantification limits were obtained. Calibration graphs were linear in the ranges 0.1-3.5, 0.2-4.5, 0.1-2.5 and 0.2-3.5 µg mL-1 with correlation coefficients of 0.9946, 0.9902, 0.9841 and 0.9936, respectively under the optimum conditions. Surfactant was used with (L2, L4) to enhance the chelation process. Interference effect of some cations and anions has been tested. The method was successfully applied to determine cadmium in food and water samples with satisfactory results compared to the ICP-AAS method. |
