Extraction and preconcentration of cadmium and zink cations using ligandless green effervescence-assisted dispersive liquid-liquid microextraction performed in a narrow-bore tube

Although heavy metal ions are present in relatively lowconcentrations in the environment, in recent years, with anincrease in city development and industry, they have beenwidely used in many industries. Among the heavy metals, cadmium and lead are potentially toxic, have no known biological function to living organisms and probably cause damages to human health even at low levels. Therefore they are of primary interest in environmental quality, waste, and food [1,2].Dispersive liquid-liquid microextraction (DLLME) is based on a ternary component solvent system. Operation simplicity, rapidity, low cost, and high enrichment factor are some of the DLLME advantages. In conventional DLLME, an extraction solvent is dispersed into an aqueous sample solution with the aid of a disperser solvent. The presence of relatively high volume of the disperser solvent makes the aqueous phase relatively nonpolar and results in an increased solubility of the target lipophilic analytes into the aqueous sample solution and relatively low extraction efficiency. Developing a reliable and environmentally friendly DLLME method in a narrow-bore tube combined with AAS for the extraction, preconcentration, and determination of Cd(II) and Pb(II) in aqueous samples was aimed. In the proposed method 25 mL deionized water containingCd (II),Pb(II), and extraction solvent was poured into a narrow bore tube (25 cm × 12 mm i.d.) which its head was the funnel shaped and its end was connected to a ground glass joint. It is noted that the optimized amount of phthalic acid and sodium bicarbonate were mixed and placed into the end glass vessel.In contact with the aqueous solution, an acid-base reaction between phthalic acid and bicarbonate was rapidly occurred and the resulted CO2 led to dispersion of the extraction solvent as tiny droplets into the aqueous solution, and a cloudy state was formed. Finally, after a short time phase separation and collection of the organic phase on the surface of the aqueous phase was occurred.The proposed method made possible the determination of the analytes in the ranges of 1.0-20 µg L-1. The accuracy of the developed method was verified by analyzing a certified reference material, namely SPS-WW2 Batch 108. Relative recoveries (80-96%, obtained at three fortification levels) confirmed the usefulness of the method for analysis of the analytes in the environmental water samples. The method was shown to be fast, reliable, and environmentally friendly with low organic solvent consumption.