STUDY ON THE POLAROGRAPHIC ADSORPTIVE WAVE OF THE COMPLEX Sn(Ⅳ)-PAN

An electroactive complex was formed between Sn(Ⅳ) and 1-(2-pyridylazo)-2-naphthol (abbreviated as PAN) in an acetate buffer of pH 4.4.A sensitive polarographic adsorptive wave was observed in the single-sweeping oscillopolarogram with its peak appeared at -0.61 V (vs.SCE).Linear relationship beween the peak current (ip) of 2nd derivative of the adsorptive wave and the concentration of Sn(Ⅳ) was obtained in the range of 5.0×10-9-2.0×10-6mol·L-1,with a detection limit of 2.0×10-9mol·L-1.The mole ratio of the complex Sn(Ⅳ)∶PAN was found to be 1 to 2.It was shown by the result of study on the reaction mechanism that the polarographic wave was produced by the reduction of PAN of the complex adsorbed on the surface of the electrode.In the application of the method to the determination of tin(Ⅳ) in some canned food samples,values of RSD′s found were less than 4%,and results of test for recovery were in the range of 98% to 103%.