Determination of Cobalt in Food, Environmental and Water Samples with Preconcentration by Dispersive Liquid-Liquid Microextraction

Abstract

A new method for the determination of cobalt was developed by dispersive liquid-liquid microextraction preconcentration and flame atomic absorption spectrometry. In the proposed approach, 1,5-bis(di-2-pyridyl) methylene thiocarbohydrazide (DPTH) was used as a chelating agent, and chloroform and ethanol were selected as extraction and dispersive solvents. Some factors influencing the extraction efficiency of cobalt and its subsequent determination, including extraction and dispersive solvent type and volume, pH of sample solution, concentration of the chelating agent, and extraction time, were studied and optimized. Under the optimum conditions, a preconcentration factor of 8 was reached. The detection limit for cobalt was 12.4 ng·mL -1, and the relative standard deviation (RSD) was 3.42% (n = 7, c = 100 ng·mL -1 ). The method was successfully applied to the determination of cobalt in food, environmental and water samples.

Evaluation of dispersive liquid-liquid microextraction for the determination of cobalt and cadmium by flame atomic absorption spectrometry: application in water and food samples

“…Sample preparation using dispersive liquid-liquid microextraction (DLLME) allows small volumes of solvent to be employed, making it an attractive "Green Chemistry" technique [18,19]. It is based on a ternary component solvent system including disperser solvent, extraction solvent, and aqueous sample containing analytes of interest [20].…”