硫氰酸盐分光光度法快速测定钼铁中钼

Quick determination of molybdenum in ferro-molybdenum by spectrophotometry with thiocyanate

研究以高氯酸铁为抑制剂，抗坏血酸为还原剂的硫氰酸盐分光光度法测定高含量钼的方法。钼铁试样用硝酸和高氯酸溶解，硫酸冒烟，盐类溶解后在高氯酸铁的存在下，以抗坏血酸还原Mo（Ⅶ为Mo（Ⅴ），Mo（Ⅴ）与硫氰酸铵生成橙色络合物，在460nm波长处测定其吸光度。用本法测定3个钼铁标样中钼，测定值与认定值相符，6次测定的相对标准偏差为0．29％～0．35％，分析时间只需50min。

A spectrophotometric method for determination of large amounts of molybdenum in ferromolybdenum with ammonium thiocyanate has been studied in the present of iron perchlorate as a depressant and ascorbic acid as a reductant. Sample is dissolved in nitric acid and perchloric acid. After adding sulfuric acid and heating until the fumes of sulfuric acid to appear, the salt is dissolved in water. Mo（Ⅵ） in the solution is reduced to Mo（Ⅴ） by ascovbic acid in the present of iron perchlorate. Mo（Ⅴ） with ammonium thiocyanate forms a orange complex, of which absorbance can be measured at the wavelength of 460 nm. Molybdenum in three ferro-molybdenum standard samples is determined by the proposed method. The results compare favourably with the certified values,giving the RSD of 0.29% -0.35% （n = 6）. The analysis of samples can be completed within 50 min.