Spectrophotometric determination of vanadium(IV) and vanadium(V) in each other's presence. Review

Speciation of vanadium in soil.

Adsorptive cathodic stripping voltammetric determination of ultra-trace concentrations of vanadium on a glassy carbon mercury film electrode

Sensitive methods for the spectrophotometric determination of trace amounts of vanadium(IV) are described. The methods utilize the ternary complexes formed by reacting vanadium(IV) with imipramine or chlorprothixene hydrochlorides in the presence of chrome azurol S and methylcellulose. The composition and the absorption spectra in the UV–VIS and IR regions of the ion association complexes are described.

Spectrophotometric determination of vanadium(iv) by ternary complexes of chrome azurol s with imipramine and chlorprothixene

Abstract A liquid-liquid extraction-chromogenic system for vanadium(IV, V) containing 2,3-dihydroxynaphtahlene (DN), 2,3,5-triphenyl-2H-tetrazolium chloride (TTC), water and chloroform was studied in detail. When the vanadium is in the oxidation state of IV, the extracted species are aggregates containing three 1:2:1 (V:DN:TTC) ion-pair units composed of triphenyltetrazolium cations (TT+) and chelate anions {[VIVO(DN)(DNH)]− (I) and/or [VIV(OH)(DN)2]− (II)}. When the initial oxidation state of vanadium is V and the DN concentration is high, vanadium(V) is reduced by DN to a lower oxidation state, V(IV). However, at low DN concentration, vanadium(V) can enter the organic phase as a part of an ion-pair consisting of TT+ and [VVO2(DN)]− (III). The ground-state equilibrium geometries of the anions I, II, and III were optimized by quantum chemical calculations using BLYP/6-31++G⋆. The following characteristics were determined under the optimum conditions for VIV extraction: absorption maximum λmax = 333 nm, molar absorptivity ε333= 2.1x104 dm3 mol−1 cm−1, Sandell’s sensitivity SS = 2.4 ng cm−2, and fraction extracted E = 98%. The conditional extraction constant was calculated by two independent methods. The calibration graph was linear in the range 0.1-3.1 μg cm−3 (R2=0.9994) and the limit of detection was 0.03 μg cm−3.

https://www.degruyter.com/downloadpdf/j/chem.2016.14.issue-1/chem-2016-0022/chem-2016-0022.xml

An extraction-chromogenic system for vanadium(IV,V) based on 2,3-dihydroxynaphtahlene

A new, sensitive and selective method for separation, and extraction - spectrophotometric determination of V (V) with pyrogallol {Ar (OH)3} and hydroxyamidines (HOA) is described. The molar absorptivities of the colored species with six substituted HOA lie in the range of (0.52–1.5)x 106 L mole−1 cm−1 at λmax 430–440 nm. Of these, the simplest compound, N-hydroxy-N, N- diphenylbenz-amidine (HDPBA) gives the most sensitive color reaction and hence, it is used for detailed studies. No interference of almost all diverse ions tested is noticed. The method offers the determination of vanadium in different environmental samples.

C. Agarwal

Papers

Sensitive Spectrophotometric Determination of Vanadium in Environmental Samples at PPB Levels