Selective method for the spectrophotometric determination of vanadium in the presence of other refractory elements with 2,2′-iminodibenzoic acid

Abstract

A selective method for the spectrophotometric determination of V in the presence of other refractory elements is proposed. It is based on the re-examination of its redox reaction with 2,2'-iminodibenzoic acid in H2SO4 medium (11.1-11.4 mol 1-1) in the presence of H3P04. Up to 1 mg of TiIV, Z P , NbV, Mow and Wvl do not interfere. V should be pre-oxidized in H2SO4 medium (S6.5 rnol 1-1) at room temperature with a 0.1% m/v solution of potassium permanganate, the excess of which is removed by adding successively 1 ml of a 10% m/v solution of urea and a few drops of a 0.1% solution of sodium nitrite. The molar absorptivity of this system was found to be 1.2 X 104 1 mol-1 cm-1 at 610 nm. The Lambert-Beer law is obeyed over the concentration range 0.4-2.0 pg ml-1 of V with the linear regression equation A = 0.0188C-0.0229 (C = pg of V per 25 ml) and correlation coefficient r = 0.9990. The standard deviation ( n = 10) and relative standard deviation at the level of 20 pg of V were found to be 0.88 pg and 4.4%, respectively. The versatility of the proposed method was demonstrated by incorporation of the preconcentration of V with N-benzoyl-N-phenylhydroxylamine as precipitant and MoV1 as carrier.

A highly sensitive spectrophotometric determination of micro amounts of vanadium(V) in environmental and alloy samples by using 3,4-dihydroxybenzaldehydeisonicotinoylhydrazone (3,4-DHBINH)

“…This method was successfully applied for the determination of vanadium(V) in environmental samples (water and soil) tobacco leaves and standard alloy samples and the results which are in good agreement with the results obtained by AAS. Salinas et al (1992) 4-Benzl-3-methyl-1-phenylpyrazole-5-one 480 -120 0.0625 Bieluonwu (1996) 3-Hydroxy-3-phenyl-1-pcarboxyphenyltriazene 395 pH 6.5-7.0 0.5-3.5 0.955 Razie et al (1994) 2,2 1 -Iminodibenzoic acid 610 Monochloroacetic acid 0.4-20 1.2 Zhou et al (1994) 3,4-Dihydroxybenzaldehyde isonicotinoyl hydrazone 360 pH 5.5 0.5-5.3 1.29 Present method…”

“…Among these, spectrophotometric methods are preferred because they are cheaper and easier to handle but with comparable sensitivity. Several spectrophotometric methods have been reported for the determination of vanadium by using various reagents (Abebaw et al 1996;Arya and Mahajan 1997;Kallol Ghosh et al 1997;Mustafa et al 1995;Iranpur et al 1992;Salinas et al 1992;Bieluonwu 1996;Razie et al 1994;Zhou et al 1994). But some of them are suffered with requiring extraction (Alemayehu and Singh 1998;Chakrabarthi 1995;Singh and Berhanu 1996) or lack of sensitivity (Bieluonwu 1996).…”