以Cu~(2+)电极为指示电极,用间接电位滴定法测定溶液中的铝,其相对误差小于2.0%。为加速反应,并使络合反应进行完全,应加入过量EDTA,并将溶液加热至沸。实验结果还表明,土壤中Ca~(2+),Mg~(2+),Mn~(2+),Fe~(3+)对测定不发生干扰。当土壤中交换性铝的含量为0.03—8mc/100g时,本法测定的相对误差低于5.0%,与经典的中和法相比,本法操作简便,终点易于判断,精密度更高。 The Cu ~ (2+) electrode was used as the indicator electrode, and the indirect method was used to measure the aluminum content in the solution. The relative error was less than 2.0%. To speed up the reaction and complete the complexation reaction, excess EDTA should be added and the solution warmed to boiling. The experimental results also show that Ca 2+, Mg 2+, Mn 2+ and Fe 3+ in soil do not interfere with the determination. When the content of exchangeable aluminum in the soil is 0.03-8mc / 100g, the relative error of this method is less than 5.0%. Compared with the classical neutralization method, this method is easy to operate, the end point is easy to judge and the precision is higher.