Spectrophotometric determination of cadmium in wastewater with 1-(4-antipyrine)-3-(sulfanilic acid)-triazene

The reaction of 1-(4-antipyrine)-3-(sulfanilic acid)-triazene(ASTA) with cadmium was studied to establish a direct photometric determination of cadmium in wastewater.The results showed that in the mixed medium of Na2B4O7-NaOH,cadmium reacted with ASTA to form a 1∶2 red complex.The complex had maximum absorption at 505 nm with the apparent molar absorptivity of 2.7×105 L·mol-1·cm-1.0.3-5.0 μg of Cd(Ⅱ) obeyed Beer's law in 10 mL of solution and the detection limit was 0.1 mg/L.This method had been applied to the determination of cadmium in wastewater samples, whose results were in consistency obtained by AAS method.Recovery was in the range of 104%-105% and the RSD(n=6) was lower than 3.9%.