LAUSR

Abstract A new, sensitive, and safe pretreatment method for the analysis of Cd(II) and Zn(II) ions in oil samples prior to flame atomic absorption spectrometry was developed. For the first time, a deep eutectic solvent is used as a disperser in reversed-phase dispersive liquid-liquid microextraction procedure. For this purpose, a deep eutectic solvent with low viscosity and miscible with both aqueous and organic phases is prepared by mixing glycolic acid and mandelic acid at a molar ratio of 2:1. The variables involved in this process were studied to provide high enrichment factors. Under optimized conditions, the linear ranges of calibration curves for Cd(II) and Zn(II) ions were obtained 0.30−20 and 0.50−30 μg L−1, respectively. The obtained detection limits and enrichment factors were 0.12 and 0.18 μg L−1; and 32.7 and 32.2 for Cd(II) and Zn(II), respectively. Repeatability of the proposed method, expressed as relative standard deviation, ranged from 2.7 to 4.1 % (n = 6, C = 1 μg L−1 of each cation). Finally, the proposed method was successfully applied for the determination of Cd(II) and Zn(II) concentrations in various oil samples.