钍-茜素氨羧络合剂极谱络合吸附波的研究

Polarographic Adsorptive Wave of Thorium-Alizarin Complexon Complex

在邻苯二甲酸氢钾和醋酸混合底液 (pH 5.0 )中 ,钍与茜素氨羧络合剂 (ALC)形成电活性络合物 ,在单扫描极谱仪上于 - 0 .60V(vs.SCE)产生一灵敏的络合吸附波 ,其二阶导数峰高与钍的浓度在 3.0× 1 0 - 8～ 3.0× 1 0 - 6 mol/L呈线性关系 ,检出限为 1 .5× 1 0 - 8mol/L。用等摩尔连续变化法测得该络合物的摩尔比为nTh(Ⅳ ) ∶nALC=1∶1 ,并探讨了极谱波的性质和电极反应机理。方法用于矿石和粘土中痕量钍的测定 ,RSD (n =5) <4% ,加标回收试验 ,回收率为1 0 1 .5%～ 1 0 3.2 %

A sensitive adsorptive wave of thorium Alizarin complexon complex has been obtained by using single sweep polarography in 3×10 -2 mol/L potassium biphthalate -0.1 mol/L acetate mixed buffer (pH 5.0) containing 1.2×10 -5 mol/L alizarin complexon. The second order derivative peak height of the complex at -0.60 V ( vs .SCE)is proportional to the concentration of Th (Ⅳ) over the range of 3.0×10 -8 ～3.0×10 -6 mol/L. The detection limit for Th (Ⅳ) is 1.5×10 -8 mol/L. The molar ratio of each component in the complex has been estimated as n Th(Ⅳ) ∶ n ALC =1 ∶ 1. The properties of the polarographic wave and the electrode reaction mechanism are also discussed in detail. The recovery of standard addition of the method for Th (Ⅳ) is 101.5%～103.2% with precision of less than 4% RSD ( n =5). The method has been applied to the determination of the trace Th (Ⅳ) in the ore and clay samples with satisfactory results.