Preconcentration of cobalt with 8-hydroxyquinoline and gas chromatographic stationary phase Chromosorb 105 and its determination by graphite furnace atomic absorption spectrometry

This paper presents a study of the adsorption characteristics of a commercially available GC stationary phase Chromosorb 105 for Co2+, which can be successfully applied to the preconcentration of Co2+ in water samples followed by GFAAS determination. After reacting with 8-hydroxyquinoline to form a complex at pH 8.0, Co2+ in water can be retained on a minicolumn packed with Chromosorb 105 and eluted with 2.5 ml of a mixture of ethanol and 2 mol l−1 HNO3 (2+1, v/v). The recoveries of Co2+ from 200 ml of tap water, river water and bottled natural mineral water samples are quantitative. Conditions for quantitative and reproducible preconcentration, elution and subsequent GFAAS determination were studied. A highly sensitive, simple method for preconcentration and GFAAS determination of trace amount of cobalt in natural water samples using a Chromosorb 105 packed minicolumn has been proposed. The high retention efficiency (∼95%) for Co2+ provides a sensitivity enhancement of 80 for a 200 ml sample volume with a detection limit of 13.4 ng l−1 (3σ) and a quantification limit of 44.5 ng l−1 (10σ).