Development of Dispersive Liquid-Liquid Microextraction Based on Solidification of Floating Organic Drop for the Determination of Trace Cobalt in Water Samples

A liquid-phase microextraction technique was developed using dispersive liquid-liquid microextraction based on solidification of floating organic drop combined with flame atomic absorption spectrometry, for the extraction and determination of trace amounts of cobalt in water samples. Microextraction efficiency factors, such as the type and volume of extraction and dispersive solvents, pH, extraction time, the chelating agent amount, and ionic strength were investigated and optimized. Under optimum conditions, an enrichment factor of 160 was obtained from 10.0 mL of water sample. The calibration graph was linear in the range of 1.15-110 mu g L-1 with a detection limit of 0.35 mu g L-1.The relative standard deviation for ten replicate measurements of 10 and 100 mu g L-1 of cobalt were 3.26% and 2.57%, respectively. The proposed method was assessed through the analysis of certified reference water or recovery experiments.