Dispersive liquid-liquid microextraction combined with flame atomic absorption spectrometry for determination of cadmium in environmental, water and food samples

A simple and reliable method for rapid and selective extraction and determination of trace levels of Cd2+ was developed by dispersive liquid-liquid microextraction (DLLME) coupled to flame atomic absorption spectrometry (FAAS) detection. The main factors affecting the DLLME, such as concentration of DPTH, pH, extraction and disperser solvent type and their volume, were optimized for the best extract efficiency. Under the optimum conditions, i.e., pH 5.4, [DPTH] = 6 x 10(-3%), a preconcentration factor of 55 was reached. The lower limit of detection (LOD) obtained under the optimal conditions was 0.4 mu g L-1. The precision for 14 replicate determinations at 30 and 100 mu g L-1 of Cd was 2.7% and 1.9% relative standard deviation (R. S. D.), respectively. The calibration graph using the preconcentration method was linear from 5 to 100 mg L-1, with a correlation coefficient of 0.9898. The proposed method was successfully applied to the preconcentration and determination of cadmium in food, vegetation, and water samples and in a BCR-176 standard reference material.