常量分析中镧的测定常采用草酸盐重量法,近年来容量分析的方法也日益增多,有用N—苯甲酰基苯胲标准溶液的滴定测定,有用钼酸钠与镧定量生成钼酸镧的安培滴定,还有不少用EDTA为滴定剂的络合滴定法.由于各类方法的局限性,在简便、快速、准确等要求方面尚欠不足.鉴于所提及的钼酸镧沉淀在pH5～6的介质中能很好地定量形成,其中La~(3+):MoO_4~(2-)=2:3,而钼酸盐可用示波滴定法 Constant analysis of lanthanum often used oxalate gravimetric method, volumetric analysis methods are also increasing in recent years, the useful N-benzoylbenzene standard solution titration, the use of sodium molybdate and lanthanum quantitative generation of lanthanum molybdate Ampere titration, there are a lot of titration with EDTA titration method.Because of the limitations of various methods, in the simple, fast, accurate and other requirements are not enough.In view of the mentioned lanthanum molybdate precipitation at pH5 ~ 6 in the medium can be well quantitatively formed, of which La ~ (3 +): MoO_4 ~ (2 -) = 2: 3, and molybdate available oscillometric titration