Photometric Determination of Trace Amounts of Vanadium by the Colour Reaction with 1-(2-Pyridylazo)-2-Naphthol and Hydrogen Peroxide

It was found that in an acidic medium of 1 mol·L-1 HCl and in the presence of CTMAB,a ternary complex,with mole ratio of 1 to 1 to 1,was formed by the reaction of V(Ⅴ) with 1-(2-pyridylazo)-2-naphthol (PAN) and hydrogen peroxide,having its absorption maximum at the wavelength of 577 nm and the value of apparent molar absorptivity of 3.04×104L·mol-1·cm-1.Beer′s law was kept in the concentration range within 1.0 mg·L-1 of vanadium(Ⅴ).The proposed method was used for determination of vanadium in 4 samples of soil,including a standard sample (GSS-5).Values of RSD′s (n=6) found were less than 9%,and results of recovery found by standard addition method were in the range of 97.8%-101.5%.Relative error between results found for the standard sample (170.45 μg·g-1) and the certified value (166±9) μg·g-1 was 2.7%.