Optimized ultrasound-assisted emulsification microextraction for simultaneous trace multielement determination of heavy metals in real water samples by ICP-OES

Ultrasonic-assisted emulsification microextraction (USAEME) combined with inductively coupled plasma-optical emission spectrometry (ICP-OES) was used for preconcentration and determination of aluminum, bismuth, cadmium, cobalt, copper, iron, gallium, indium, nickel, lead, thallium and zinc in real water samples. Ammonium pyrrolidine dithiocarbamate (APDC) and carbon tetrachloride (CCl4) were used as the chelating agent and extraction solvent, respectively. The effective parameters (factors) of the extraction process such as volume of extraction solvent, pH, sonication time, and concentration of chelating agent were optimized by a small central composite design (CCD). The optimum conditions were found to be 98 μL for extraction solvent, 1476 mg L−1 for chelating agent, 3.8 for pH and 9 min for sonication time. Under the optimal conditions, the limits of detection (LODs) for Al, Bi, Cd, Co, Cu, Fe, Ga, In, Ni, Pb, Tl and Zn were 0.13, 0.48, 0.19, 0.28, 0.29, 0.27, 0.27, 0.38, 0.44, 0.47, 0.52 and 0.17 μg L−1, respectively. The linear dynamic range (LDR) was 1–1000 μg L−1 with determination coefficients of 0.991–0.998. Relative standard deviations (RSDs, C=200 μg L−1, n=6) were between 1.87%–5.65%. The proposed method was successfully applied to the extraction and determination of heavy metals in real water samples and the satisfactory relative recoveries (90.3%–105.5%) were obtained.