Development of an air-assisted liquid-liquid microextraction method based on a ternary solidified deep eutectic solvent in extraction and preconcentration of Cd(II) and Zn(II) ions

Abstract

A green, simple, rapid, and efficient ligandless air-assisted liquid-liquid microextraction procedure based on solidification of a ternary deep eutectic solvent was developed for the extraction of trace amounts of cadmium(II) and zinc(II) ions in aqueous samples prior to their determination by flame atomic absorption spectrometry. For this purpose, the deep eutectic solvent is formed by mixing sorbitol, menthol, and mandelic acid at a suitable mole ratio and after heating for a short time, a deep eutectic solvent with low density compared to water is synthesised. The synthesised solvent is used as a chelating agent and also as an extraction solvent. Under the optimum experimental conditions, the linear ranges were obtained in the ranges of 0.5–12.5 and 0.5–10.0 µg L−1 for Zn(II) and Cd(II), respectively. The relative standard deviations (n = 6, C = 2.5 µg L−1 of each cation) were 4.2% and 3.4%, for Cd(II) and Zn(II), respectively. Moreover, the obtained detection limits were 0.15 and 0.12 µg L−1 for Cd(II) and Zn(II), respectively. The accuracy of the developed method was studied by analysing SPS-WW2 Batch 108 water as a certified reference material. Finally, the proposed method was successfully applied in the determination of Cd(II) and Zn(II) ions in water and fruit juice samples.Abbreviations: AALLME: Air-assisted liquid-liquid microextraction; ER: Extraction recovery; FAAS: Flame atomic absorption spectrometry; LOD: Limit of detection; LOQ: Limit of quantification; RSD: Relative standard deviation