在乙酸-乙酸钠缓冲溶液中(pH 4.4),锡与1-(2-吡啶偶氮)-2-萘酚(PAN)形成电活性络合物,在单扫描极谱仪上,于-0.61 V(vs.SCE)处产生一灵敏的导数极谱波,其峰电流与5.0×10-9-2.0×10-6mol·L-1锡浓度呈线性关系,检出限达2.0×10-9mol·L-1.用等摩尔连续变化法测得络合物的摩尔比为nSn(Ⅳ)∶nPAN=1∶2.机理研究表明,极谱波为吸附在电极表面的络合物中PAN还原产生.此法可用于测定罐头食品中锡,测定结果的RSD值小于4%,回收率为98%-103%.

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%.