ｐ‐ヒドラジノベンゼンスルホン酸とｍ‐フェニレンジアミンとの酸化カップリング反応を利用する微量バナジウム（Ｖ）の接触分析法

Abstract

A new catalytic method is proposed for the determination of trace amounts of vanadium ( V)In the presence of chlorate, vanadium ( V ) catalyzed the oxidation of p-hydrazinobenzenesulf onic acid to p-sulfobenzenediazonium ion which was then coupled with m-phenylenediamine to form a yellow azo dyestuff (λmax 454 nm). By measuring the absorbance of the dyestuff at 454 nm, trace amounts of vanadium(V) can be determined. Under the experimental condition s established, a linear working curve was obtained with the effective molar absorptivity of 9.9×105 dml3/mol⋅cm. The reproducibility of the method was satisfactory with c. v. (%) of 2.1, 2.7and 2.0 for four determinations of 0.20, O.60 and 1.00μg of vanadium (V), respectively. It was also, found that higher sensitivity could be obtained by adding tartaric acid as an activator in the reaction system. In this case, the effective molar absorptivity was 1.4×106dm3/mol⋅cm. Positive interferences were observed from more than 5μg of iron (II), iron(III) or selenium (IV). One μg of each copper(II) and molybdenum(IV) also caused a positive interference. Ten μg of aluminum(III) yielded a negative interference.