Chemiluminescence Flow System for Vanadium(V) With Immobilized Reagents

Abstract

A chemiluminescence (CL)-based system for vanadium(V) combined with flow-injection analysis is described. The analytical reagents, luminol and hexacyanoferrate(II), were both immobilized on an anion-exchange resin column. When a volume of phosphoric acid was passed through the column, these two reagents were eluted from the resin and then mixed with a vanadium(V) stream under acidic conditions. By means of the fast oxidation reaction between vanadium(V) and hexacyanoferrate(II), vanadium(IV) and hexacyanoferrate(III) were generated, both of which catalyzed the oxidation of luminol by dissolved oxygen in aqueous alkaline solution to produce CL. The CL emission intensity was correlated with the standard vanadium(V) concentration in the range from 1.0 × 10 ^{- 2} to 10 µg cm ^{- 3} , and the detection limit was 5.4 × 10 ^{- 3} µg cm ^{- 3} vanadium(V). Interfering metal ions co-existing in sample solutions could be effectively separated on-line by a cation-exchange column placed upstream. A complete analysis, including sampling and washing, could be performed in 1 min with a relative standard deviation of less than 5%. The system was stable for over 100 analyses and was applied successfully to the determination of vanadium in geochemical and human hair samples.