SENSITIVE SPECTROPHOTOMETRIC DETERMINATION OF TRACE AMOUNTS OF VANADIUM (IV, V) USING DITHIOLPHENOLS AND HYDROFOB AMINS

Dithiolphenole (DP) has been synthesized and characterized with IR and NMR spectroscopic methods. A simple and spectrophotometric method has been developed for the determination of trace amounts of vanadium (IV, V). The reagents forms blue coloured insoluble in water complex with vanadium (IV, V) in a weakly acidic and slightly alkaline medium (pH 2.5 - 8.5). In the presence of hydrophobic amines (Am) form ternary complexes. As hydrophobic amine-phenantroline (Phen), batophenantroline (BPhen) and dipiridile (Dip) were used. The molar absorptivity of coloured species are (2.95 - 3.85) x 10(4) L.mol(-1) cm(-1) . Beer's law is obeyed in the range 0.2 - 18 mu g/ml of vanadium (IV, V) at lambda(max) , 610 - 630 nm. Vanadium (IV, V) forms 1: 1: 1 complex with DP and Am, stability constant of the complex was found to be 9.58 - 10.95 (pH(opt) = 6.4 - 7.9). The proposed method was successfully applied to the analysis of vanadium in soil, natural water samples and plant material. The results obtainned were agreed with the reported methods at the 98% confidence level. The optimum reaction conditions and other analytical parameters were investigated to enhance the sensitivity of the present method. The detailed study of various interferences made the method more selective.