Document Type : Research Article
Department of Chemistry, Maragheh Branch, Islamic Azad University, Maragheh, I.R. IRAN
Department of Chemistry, Payame Noor University (PNU), Tehran, I.R. IRAN
In this research, a simple, fast, inexpensive, and efficient microextraction method called Vortex Assisted -Solidified Floating Organic Drop MicroExtraction (VAE-SFODME) in pre-concentration and separation of ultra-trace amount of cadmium from aqueous environmental, biological, and food samples was studied. In this method, cadmium metal forms a complex with ammonium pyrrolidine dithiocarbamate (APDC) and is extracted into the organic phase, 1-dodecanol. After the phase separation, the enrichment analyte is determined by electrochemical atomic absorption spectroscopy. The use of vortex as a useful tool eliminated the organic solvent of the disperser, while also distributing fine extracting solvent in the solution and increasing the contact surface, increasing the extraction efficiency and the enrichment factor. Solvent 1-dodecanol was chosen as a suitable extraction solvent due to the proper melting point and low density than water. Experimental parameters related to extraction efficiencies such as extraction solvent volume, pH, the concentration of the chelating agent, extraction time, centrifuge condition, salt concentration, and the effect of interference ions were studied. Under the optimized conditions (Extraction solvent (1-dodecanol); 90 μL, pH =2.5, APDC; 12 μL, extraction time; 3 min, centrifugation speed 4000 rpm for 2 min, no salt added, and at room temperature) detection limit (S/N=3), determination limit, reproducibility (RSD, n=5) and enrichment factor were 0.58 ng/mL, 1.92 ng/mL, 0.97% and 96 respectively. Meanwhile, in order to study the accuracy of the proposed method, environmental samples (refined water, urban water, and river water) and biological samples including human saliva and saliva, and salts with cadmium levels at concentrations of 20 and 40 ng/mL spiked, the recovery of spiked samples were very good and were in the range of 94.5-101.3%. Therefore, the proposed method can be used successfully in various aquatic, biological, and food samples.