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本文研究了在有聚乙烯醇的情况下,用磷钼杂多酸-罗丹明B作试剂,水相分光光度测定不同价态的钒。V(V)与试剂形成四元络合物R_4[Mo_11V(V)PO_(40)]:V(Ⅳ)无显色反应;V(Ⅲ)还原磷钼杂多酸成磷钼蓝,再与罗丹明B形成三元络合物R_5[Mo_(11)(Ⅳ)Mo_2(V)PO_(40)]过剩磷钼杂多酸可加入柠檬酸掩蔽。当V(Ⅳ)与V(V)共存时,将其氧化成V(V),测合量后差减得V(Ⅳ)含量:当V(Ⅳ)与V(Ⅲ)共存时,将其还原成V(Ⅲ),测合量后差减得V(Ⅳ)含量。试剂最大吸收峰在555毫微米外,两种络合物最大吸收峰都在586毫微米处,结合物的摩尔吸光系数分别为2.80×10~5和2.16×10~5.0—3.0微克V(V)和0—4.0微克V(Ⅱ)/25毫升遵守比尔定律。
In this paper, the presence of polyvinylalcohol, phosphomolybdic heteropoly acid - rhodamine B as a reagent, aqueous phase spectrophotometric determination of different valence vanadium. V (V) and reagent to form quaternary complex R_4 [Mo_11V (V) PO_ (40)]: V Rhodamine B forms a ternary complex R_5 [Mo_ (11) (Ⅳ) Mo_2 (V) PO_ (40)] Excess phosphomolybdic heteropolyacid can be masked by citric acid. When V (IV) coexists with V (V), it is oxidized to V (V) and the difference is reduced to V (IV) Reduced to V (Ⅲ), after measuring the amount of difference to V (Ⅳ) content. The maximum absorption peak of the reagent was 555 nm, the maximum absorption peak of both complexes was at 586 nm, and the molar absorptivities of the complexes were 2.80 × 10 -5 and 2.16 × 10 -5.0-3.0 μg V (V ) And 0-4.0 micrograms of V (II) / 25 milliliters of Beer’s law.