Determination of cadmium in tableware leach solution by spectrophotometry using 2,6-dimethylphenyldiazoaminobenzene

A sensitive and selective spectrophotometric method has been developed for determination of trace cadmium in tableware leach solution, the method based on the reaction of cadmium(II) with new reagent 2,6-dimethylphenyldiazoaminobenzene (DMPDAAB). In 0.2 mol l−1 ammonia medium, DMPDAAB reacts with cadmium(II) to form 1:3 red complex with a maximum absorption peak at 523 nm. The apparent molar absorption coefficient of the complex and Sandell’s sensitivity were 2.27 × 105 l mol−1 cm−1 and 0.495 ng cm−2, respectively. The detection limit for cadmium and relative standard deviation were found to be 0.18 ng/g and 1.06%, respectively. Under optimal conditions, the reaction can complete instantly and absorbance of the complex remain stable for 12 h at least. Absorbance of the complex at 523 nm obey Beer’s law in the cadmium(II) range of 0–0.48 μg/ml. Moreover, we also studied the effect of foreign ions on the determination of cadmium in detail, the results showed the method has excellent selectivity, it has been applied to determine cadmium in tableware leach solution satisfactorily.