Spectrophotometric determination of cadmium(II) using p,p'-dinitro-SYM-diphenylcarbazid in aqueous solutions

A sensitive and selective spectrophotometric method is proposed for the rapid determination of cadmium(II) using, p,p'-dinitro-sym-diphenylcarbazid, directly in aqueous solution. The reaction between cadmium(II) and p,p'-dinitro-sym-diphenylcarbazid occurs immediately in strong basic media (0.02 N sodium hydroxide solution). The complex shows a maximum of absorption at 630-640 nm, and the absorbance remains stable for at least 24 h. The method allows the cadmium determination over the range 0.5-6.0 mu g mL(-1) , with a molar absortivity of 2.05x10(4) L mol(-1) cm(-1) and features a detection limit of 0.13 ppm. The interferences caused by several ions [Ca(II), K(I), Ba(II), Al(III), Pb(II), Zn(II), Cl-1 , NO3- , SO42-], which are present in most of environmental samples, were determined. The validation of the spectrophotometric method was done by recovery test of cadmium(II) in tap water and sea water. The results show that the proposed method has been successfully applied to the determination of cadmium(II) in water samples.