Development of ultrasound-assisted emulsification microextraction for the determination of trace zinc and copper by flame atomic absorption spectrometry

In this work, we developed a method based on ultrasound-assisted emulsification microextraction (USAEME) for the determination of zinc and copper by flame atomic absorption spectrometry (FAAS). The method is based on the use of the organic solvent carbon tetrachloride (CCl4) as an extraction solvent. In order to obtain a high enrichment factor, the effect of different parameters affecting the complex formation and extraction conditions (such as the type and volume of the extraction solvent, pH, the chelating agent amount, extraction time, extraction temperature and ionic strength) were tested. Under optimum conditions, the eight replicates mixture of the 100 ngmL^-1 and 50 ngmL^-1 for Zn(II) and Cu(II) ions, gave a mean absorbance of 0.055 and 0.061, with a relative standard deviation (RSD) of ±%3.2 and 2.9, respectively. The equations for the lines were A = 0.4921C + 0.0027 (R = 0.9998) and A = 1.0701C + 0.0032 (R = 0.9997), respectively. The limit of detection for Zn (II) and Cu(II) ions were 1.06 and 1.4 ngL^−1, respectively. The calibration graph was linear in the range of 3.0–2000.0 ngmL^−1 and 2.0-850.0 ngmL^−1 for Zn and Cu respectively. In the proposed procedure, enhancement factors were 9.51 and 6.25 for Zn and Cu, respectively. This proposed method was successfully applied in the analysis of four real environmental water samples and good spiked recoveries over the range of 98.4–103.0% were obtained. This is the first research using USAEME for simultaneous determination of Zn and Cu in water.