A procedure for determination of cobalt in water samples after dispersive liquid-liquid microextraction

In this work, a procedure for preconcentration of cobalt using dispersive liquid-liquid microextraction (DLLME) with the reagent Br-TAO as complexing reagent was developed. The procedure is based on a ternary system or solvents, where appropriate amounts of the extraction solvent, disperser solvent and the chelating agent Br-TAO are directly injected into an aqueous solution containing Co(II). A cloudy mixture is formed and the ions are extracted in the fine droplets of the extraction solvent. After extraction, the phase separation is performed with a rapid centrifugation, and cobalt is determined in the enriched phase by FAAS. Under the optimized conditions, the detection limit obtained was 0.9 mu g L-1. The enrichment factor and the consumptive index were 16 and 0.31 mL, respectively. The accuracy of the method was tested by the determination of cobalt in certified reference material of spinach leaves. NIST 1570a. The proposed procedure was successfully applied to the determination of cobalt in water samples. (C) 2009 Elsevier B.V. All rights reserved.