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ICP-OES determination of some heavy metal residues in milk samples by dispersive liquid–liquid microextraction; application of newly synthesized deep eutectic solvent as a complexing agent and extraction solvent

Mahdi Rouhi, Jafar Abolhasani, Mohammad Reza Afshar Mogaddam, and Mohammad Taghi Vardini

Department of Chemistry, Tabriz Branch, Islamic Azad University, Tabriz, Iran



Received: 24 September 2022  Accepted: 22 July 2023


In the present study, a combination of homogeneous liquid–liquid extraction and dispersive liquid–liquid microextraction has been employed for the extraction of some heavy metals (Co, Ni, Cu, Zn, Pb, Cd and Hg) from milk samples. In the extraction process, first, an appropriate amount of sodium chloride is dissolved in the milk sample and after that a mixture of acetonitrile and ternary deep eutectic solvent (prepared from choline chloride, sulfosalicylic acid, and 8-hydroxyquinoline) is added. After manual shaking and centrifuging, the upper phase containing the analytes is taken and injected into deionized water. In the following, the resulted mixture is sonicated to acquire a cloudy state and efficient preconcentration. After centrifuging, the deep eutectic solvent containing the extracted analytes is sedimented at the bottom of tube. The extracted and enriched analytes are determined using inductively coupled plasma–atomic emission spectrometry. Under the optimum conditions, low limits of detection (0.04–0.10 ng mL−1) and quantification (0.12–0.34 ng mL−1), high extraction recoveries (70–83%), and good repeatability (relative standard deviations equal or less than 3.6 and 4.7% for intra- and inter-day precisions, respectively) were acquired. Finally, the offered method was employed for the determination of the studied heavy metals in various milk samples marketed in Tabriz, Iran.

Keywords: Dispersive liquid–liquid microextraction; Inductively coupled plasma-optical emission spectrometry; Heavy metal; Milk

Full paper is available at

DOI: 10.1007/s11696-023-02998-8


Chemical Papers 77 (12) 7421–7429 (2023)

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