Ligandless-ultrasound-assisted emulsification-microextraction combined with inductively coupled plasma-optical emission spectrometry for simultaneous determination of heavy metals in water samples

In the present study, the simple and efficient method of ligandless-ultrasound-assisted emulsification-microextraction (LL-USAEME) has been developed for the simultaneous preconcentration and determination of chromium and zinc in water samples by inductively coupled plasma-optical emission spectrometry (ICP-OES). Tetrachloroethylene was selected as the extraction solvent. A fractional factorial design (2(5-1)) and a Box-Behnken design (BBD) were used to identify and optimize the most important parameters that influence the ultrasound microextraction process. The optimum levels of the effective parameters were: 190 mu L for volume of extraction solvent, 11.4 for pH, 15% (w/v) for the salt concentration and 5 min for sonication time. Under the optimum conditions, the relative standard deviations (RSDs, C 100 mu g L-1, n - 7) were 2.5% and 3.1% for Cr and Zn respectively. The calibration graphs were linear in the range of 0.5-1500 mu g L-1 for both the metal ions with determination coefficients (R-2) of 0.997. The limits of detection (LODs) for Cr and Zn were 0.20 and 0.28 mu g L-1, respectively. The proposed method was successfully applied to the analysis of three real environmental water samples and satisfactory recoveries (90-109%) were achieved.