重铬酸钾法测定防锈颜料亚磷酸锌中的亚磷酸根

Determination of Phosphite Content in Zinc Phosphite by Potassium Bichromate Method

亚磷酸锌是一种优秀的防锈颜料，广泛应用于涂料行业当中。根据亚磷酸根具有还原性，设计在硫酸介质中，用重铬酸钾溶液氧化亚磷酸根，过量的重铬酸钾用硫酸亚铁铵反滴定，1，10-菲绕啉作为指示剂确定滴定终点。此方法测定亚磷酸根含量，在8～72mg呈良好的线性关系，检出限为8mg，相对标准偏差（RSD）〈1．27％，回收率在99．87％～100．22％，方法简便、可靠，可在实际中应用。

Zinc phosphite was an excellent preservative pigment which was extensively applied in coating industry. In terms of the reductibility of phosphorous acid, the phosphorous acid was oxidized with potassium bichromate in sulfuric acid. Excessive potassium bichromate could be titrated with ammonium ferrous sulfate, and 1, 10-phenanthroline indicated the end point of titration and estimated the phosphorous acid content. A good linear relationship was presented between 8-72 rng. The detection limit was 8mg and the relative standard deviation was less than 1.27 %. The recovery rate was between 99.87 % - 100.22 %.