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A simple and sensitive spectrophotometric method for vanadium(v) through a nucleophilic coupling of catechol with p-tolidine / o-tolidine

B.Shyla, C.Vijay Bhaskar, M.A.Sathish, G.Nagendrappa

A simple and sensitive spectrophotometric method is developed for the determination of vanadium and used for its determination in water samples of certain lakes that are situated in and around Mysore city and a pharmaceutical sample. The method is based on the catechol oxidation by vanadium(V) followed by its nucleophilic coupling with p-tolidine system1 or o-tolidine system 2 producing a dye with max 540nm/520nm in 0.1M hydrochloric acid. The system is obeying the BeerÂ’s law in the range 1-20 µg ml-1of vanadium. The molar absorptivity Sandell sensitivity and regression coefficient values are found to be 1.733X103 lmol-1cm-1, 0.0294 µgcm-2 and 0.9901 for p-tolidine system, and the corresponding values for the otolidine systemare 1.84 X 103 l mol-1 cm-1, 0.0276 µg cm-2 and 0.9673. The optimum reaction conditions and other analytical parameters are investigated to enhance the sensitivity of the method. The compositions of the dye product of both systems are determined by JobÂ’s method of continuous variation aswell asmole ratiomethod and are found to be 1:1 and 2:1 for the sytem 1 and 2 respectively. The method is working successfully for the analysis of vanadium present in water and pharmaceutical samples. The results of vanadium obtained from both the systems are found to be reproducible and also agreeingwith the results determined froman officialmethod.