金属钼制品样品用硝酸-硫酸混合酸溶解,钼酸盐及氧化钼等直接用氨水溶解。在0.5 mol·L-1硫酸介质中加入过氧化氢使样品溶液中的磷完全氧化至正磷酸状态,加入钼酸铵与正磷酸生成磷钼杂多酸,用正丁醇-三氯甲烷(1+3)混合溶剂萃取磷钼杂多酸。将有机相分出并用正丁醇定容至25 mL,加100 g·L-1氯化亚锡溶液1滴,将磷钼杂多酸还原为钼蓝,在波长620 nm处测其吸光度。用磷标准溶液制作标准曲线,磷的质量浓度在0.48 mg·L-1范围内呈线性。应用此方法分析了钼粉和三氧化钼样品,并做了加标回收试验,测得回收率在95.0%~103%之间,测定值的相对标准偏差(n=11)在5.8%~11%之间。

Sample of metal molybdenum product was dissolved with HNO3-H2SO4 mixed acid, while sample of salt or oxide of molybdenum (i.e., molybdates, oxides and etc.,) was dissolved with aqua ammonia. In 0.5 mol·L-1 H2SO4 medium, phosphorus in the sample solution was oxidized to orthophosphate by H2O2, and upon addition of ammonium molybdate, phospho-molybdic acid was formed, which was extracted into organic phase with mixed solvent of n-butanol and CHCl3(1+3) and the organic phase was separated and made up to 25 mL with n-butanol. One drop of 100 g·L-1 SnCl2 solution was added to reduce the phospho-molybdic acid to molybdenum blue, and its absorbance was measured at the wavelength of 620 nm. Standard curve was prepared by using standard phosphorus solution and the linearity range within 0.48 mg·L-1 was used in this method. Samples of molybdenum powder and molybdenum oxide were analyzed by the proposed method, test for recovery was made by standard addition method, giving values of recovery in the range of 95.0%-103%, and RSD′s (n=11) in the range of 5.8%-11%.