Extraction and spectrophotometric determination of vanadium with erio-chrome in presence of a cationic surfactant

Abstract

A method for extraction and spectrophotometric determination of vanadium at the 0.05-0.8 <em>&mu;</em>g ml^-1 level is described. Vanadium (V) is first extracted with N-phenylbenzohydroxamic acid into chloroform and then back-extracted with 0.1 <em>M </em>NaOH with simultaneous reduction of V(V) to V(IV) in buffer medium (<em>p</em>H 4.7) by ascorbic acid and formation of a ternary complex with eriochrome cyanine R (ECR) and cetyltrimethylammonium bromide (CTAB). Addition of cationic surfactant such as CTAB improves sensitivity of the determination, giving a molar absorptivity for ternary V(IV)-ECR-CTAB complex of 6.81 10⁴ dm³ mol^-1 cm^-1 at 575 nm.