氯代磺酚C分光光度法测定钒钛磁铁矿中铌

Determination of niobium in vanadium-titanium magnetite by chlorosulfophenol C spectrophotometry

在采用氯代磺酚C分光光度法测定钒钛磁铁矿中铌时,存在试样较难分解的问题,同时试样中的钛易水解干扰显色,钒也会与氯代磺酚C发生络合反应从而干扰测定。实验采用盐酸-氢氟酸-硫酸(1+1)溶解试样,通过加入酒石酸作为掩蔽剂消除了钛和钒的干扰,实现了氯代磺酚C分光光度法对钒钛磁铁矿中铌的测定。实验表明,在0.5~3.0mol/L盐酸介质中,铌的质量浓度在0.050~0.500μg/mL范围内与其对应的吸光度符合比尔定律,相关系数为0.9999。方法的检出限为0.002%(质量分数),测定下限为0.005%(质量分数)。干扰试验表明,试样中共存元素对铌测定的干扰可忽略。采用实验方法测定3个钒钛磁铁矿试样中铌,结果的相对标准偏差(RSD,n=6)小于1.0%。按照实验方法测定6个钒钛磁铁矿样品,结果与电感耦合等离子体原子发射光谱法(ICP-AES)相吻合。

During the determination of niobium in vanadium-titanium magnetite by chlorosulfophenol C spectrophotometry, there was a problem of the difficult sample decomposition. Meanwhile, titanium in sample was easily hydrolyzed to interfere with the coloration, and vanadium could also complex with chlorosulfophenol C to interference with the determination. After the sample was dissolved with hydrochloric acid-hydrofluoric acid sulfuric acid (1+1), tartaric acid was added as masking reagent to eliminate the interference of titanium and vanadium. Consequently, the determination of niobium in vanadium-titanium magnetite by chlorosulfophenol C spectrophotometry was realized. The results showed that the Beer′s law was obeyed between the mass concentration of niobium in range of 0.050-0.500 μg/mL and its corresponding absorbance in 0.5-3.0 mol/L hydrochloric acid medium. The correlation coefficient was 0.999 9. The detection limit of method was 0.002%(mass fraction), and the lower determination limit was 0.005%(mass fraction). The interference tests indicated that the interference of coexisting elements in sample with the determination of niobium could be ignored. The content of niobium in three vanadium-titanium magnetite samples was determined according to the experimental method. The relative standard deviations (RSDs, n =6) of determination results were less than 1.0%. Six vanadium-titanium magnetite samples were determined according to the experimental method, and the found results were in good agreement with those obtained by inductively coupled plasma atomic emission spectrometry (ICP-AES).