Optimization of magnetic solid phase microextraction with CoFe2O4 nanoparticles unmodified for preconcentration of cadmium in environmental samples by flame atomic absorption spectrometry

A method of preconcentration based in the magnetic solid phase microextraction with CoFe2O4 nanoparticles for the determination of cadmium in oyster and water samples using flame atomic absorption spectrometry (FAAS). Magnetic nanomaterials ones have aroused a greater interest in the area of analytical chemistry because of the high area of material and separation facility of the adsorbent. The statistical significance variables, extraction time, nanoparticles mass, pH, eluent concentration and desorption time were evaluated using a fractional factorial design of two levels (2(5-1)). Afterward, a design Doehlert was used to optimize the pre-concentration process. The best experimental conditions were: nanoparticles mass (25 mg), pH (10.0) and eluent concentration of 1.20 mol L-1. The method allowed the determination of cadmium with a LOD of 0.24 mu g L-1 and LOQ of 0.80 mu g L-1. The precision expressed as relative standard deviation (RSD) of 3.33% for cadmium concentration with 20 mu g L-1, the accuracy of the method was confirmed by the analysis of materials certified reference NIST 1566b Oyster tissue, pre-concentration factor 31. The method was applied to the analysis of the oyster and water samples has determined the concentration of cadmium from 4.6 to 7.8 mg kg(-1) for oyster and 2.75 to 4.8 mu g L-1 for water.