Catalytic Spectrophotometric Determination of Picogram Amounts of Vanadium in Natural Fresh and Tap Water by Flow Injection Analysis

摘要

A highly sensitive spectrophotometric FIA method is proposed for the determination of vanadium using the vanadium-catalyzed oxidation of o-phenylenediamine with bromate at pH 4.0 and 50°C in the presence of gallic acid as an activator. The same calibration graph with a linear range of 0-8μg l-1 was obtained for V(IV) and V(V) by the proposed method. The detection limit and typical sampling frequency were 4ng l-1(0.8pg) and 30 samples h-1, respectively. Iron ions of up to 5μg l-1 and humic acid of up to 3000μg l-1 were tolerable in the determination of 0.2μg l-1 of vanadium; the latter value was markedly improved compared to that with a manual-batch fluorometric method. The proposed method was successfully applied to analyses of lake, river, ground, rain and tap water samples containing vanadium down to 0.02μg l-1