SPECTROPHOTOMETRIC DETERMINATION OF VANADIUM (IV, V) USING DITHIOLPHENOLS AND AMINOPHENOLS

Dithiolphenole (DP) has been synthesized and characterized with IR and NMR spectroscopic me­thods. A simple and spectrophotometric methods has been developed for the determination of trace amounts of vana­di­um (IV, V). The reagents forms an blue coloured insoluble in water complex with vanadium (IV, V) in acidic medium (pH 2.5-8.5). In the presence of hydrophobic amines form ternary complexes. As hydrophobic amine 2,6-bis (N, N-di­me­thylaminomethyl)-4-methylphenol(AP₁),2 (N, N-diethylaminomethyl)-4-bromophenol(AP₂), 2,6-bis (N, N-di­me­thy­laminomethyl)-4-chlorophenol (AP₃), 2(N, N-diethylaminomethyl)-4-methylphenol(AP₄) were used. The molar ab­sor­ptivity of coloured species are (3.53-4.15)×10⁴ L.mol^-1 cm^-1. Beer’s law is obeyed in the range 0.2–16 μg/ml of vanadium (IV, V) at λ_max 614-630 nm. Va­nadium (IV, V) forms 1 : 2 : 2 and 1:2:1 complex with DP and Am, stability constant of the complex was found to be 9.58-10.95 (pH_opt = 6.5-7.9). The proposed methods 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.

Key words: New chromogenic reagents, spectrophotometry, vanadium(IV,V), soil, water and biological samples.