三元络合物微分阳极溶出伏安法测定亚硝酸根

Differential Anodic Stripping Voltammetric Method of Ternary Complex for the Determination of Nitrite

基于NOi_2^-可以与Pb^(2+)和SCN^-形成稳定的三元络合物,NO_2^-的存在会抑制Pb^(2+)的还原富集,使铅的微分溶出峰电流i_p~′减小,根据其减小值△i_p~′,可以间接测定NO_2^-。工作电极为玻碳电极,预电解电位为—0.75V(vs. SCE),铅的溶出峰电位为—0.5V(vs. SCE)。本文对测定条件,干扰及其消除方法进行了研究。测定下限为2×10^(-11) mol/L,大量硝酸根不干扰。

A sensitive method for the indirect determination of trace nitrite has been developed. Electrode position was established on the surface of glassy carbon electrode at -0. 75 V(vs. SCE) in base solution conataining Pb( Ⅱ ) and SCN-. A stripping peak current of lead ip' at -0. 5 V was shown by potential scanning reversely. Then added sample solution containing excess NOi' into the base solution. Ternary Complex of Pb( Ⅱ ) -NO2- -SCN- was formed. The stripping peak currnd of lead was decreased(Δip' ), and varied linearly with the concentration of nitrite and the large amounts of nitrate do not interfere with the determination. The detection limit is 2×10-11mol/L