工业硝酸钠含量的测定方法研究

Research on determination methods of industrial sodium nitrate content

研究了工业硝酸钠含量的测定方法。其原理为:硝酸钠试样在浓硫酸的存在下,其中的硝酸根与过量尿素发生反应,过量尿素在硫酸作用下水解成硫酸铵,加入一定量的中性甲醛,硫酸铵与甲醛反应生成定量的酸,用碱标准溶液滴定生成的酸,根据消耗碱标准溶液的体积,计算出硝酸钠含量。所得结果和国标法(真值)比较,相对误差在0.4%以内,具有较高的准确度和精密度。对测定条件做了正交实验,选择了最佳实验条件。通过实验,说明了这种方法的可行性。

A sensitive method for the determination of the content of industrial sodium nitrate was studied. Its principle is ：the nitrate radical of sodium nitrate sample react with superfluous urea in the presence of concentrated sulfuric acid. The superfluous urea is hydrolyzed into ammonium sulfate under the action of sulfuric acid. Then add a certain amount of neutral methyl aldehyde. The ammonium sulfate will react with methyl aldehyde and mensurable acid will be produced. Use alkaline titrating solution to titrate the produced acid. The content of sodium nitrate can be calculated according to consumed alkaline titrating solution. Compared with the true value obtained by international method, the relative error of the test result with this method did not go beyond 0.4%. Therefore, it has relative high accuracy and precision. Orthogonal tests were made on the determination conditions and the optimum experimental conditions were confirmed. The feasibility of this method was proved through experiments.