Determination of Cobalt in Some Plants by Reversed-Phase High Performance Liquid Chromatography

Abstract

The separation and determination of cobalt chelate with 4-(2-pyridylazo)resorcinol (PAR) by reversed-phase HPLC was investigated. The Co(III)-PAR chelate was separated on a C₁₈ siloxane bonded phase and eluted within 5.4 min with methanol-water-acetonitrile (1 × 10^-2 mol L^-1) and sodium acetate (55:40:2.5:2.5 v/v) containing 5 × 10^-3 mol L^-1 ethylenedi-aminetatraacetic acid (EDTA) (pH 7.5). The detection limits of Co(III) at 520 nm are 1.2 μg L^-1. The method was applied to the determination of cobalt in some samples of plants. The contents of cobalt in the plants samples were found in the ranges, 0.941-0.141 mg/kg (dry matter). Rosa canina is rather rich in cobalt and is recommended as a source.