磷钼蓝光度法测定石英岩中磷

Determination of Phosphorus in quartzite by Phosphorus Molybdenum Blues Photometry

针对石英岩类样品,用硝酸氢氟酸溶样,加硫酸冒烟除尽硝酸氢氟酸,分取适量样品加钼酸铵生成磷钼杂多酸,用抗坏血酸还原成磷钼蓝,控制硫酸酸度在0.6mol/L~1.0mol/L时,残留硅和过量的钼酸铵不参与显色,加碘化钾和酒石酸钾钠分别消除少量砷和金属阳离子的干扰,显色后的磷钼蓝可保留24h。在最优实验条件下,吸光度与五氧化二磷的线性回归方程为A=0.9058ρ+0.0051,相关系数为R2=1.0000,检出限可达0.0002%。对样品分析结果显示相对标准偏差在0.62%~1.39%之间,国家标准样品与认定值一致,能够满足石英岩中五氧化二磷的测定。

An amout of quartzite sample dissolved with nitric acid and hydrofluoric acid is transformated into phosphomolybdic heterropoly acid in the presence of ammonium molybdate followed by reducing to Phosphorus Molybdenum Blues by ascorbic acid.It can be keeping 24h,the residual silicon and ammonium molybdate do not take place in color reaction in the condition of concentration range of sulfuric acid controlling 0.6~1.0mol/L,and the interference of a small amount of arsenic and positive ion can be eliminated by addition of potassium iodide and seignette salt.In the optimal experimental conditions,equation of linear regression of absorbance and phosphorus pentoxide is A=0.9058ρ+0.0051,the coefficient of association(R2)is 1.0000,detection limit is 0.0002%.According to analysis results,it is can be used to detect phosphorus pentoxide as therelative standard deviation in the range of 0.62%~1.39%and being incongruous with the national standard sample.