Development of ligandless dispersive micro-solid-phase extraction method based on NH 2 -UiO-66 (Zr) MOF using DES eluent in determination of Cd(II) and Cu(II) ions in water and fruit juice samples

A metal–organic framework (MOF) was synthesised and used for dispersive micro-solid-phase extraction of heavy metal ions from fruit juice and water sample without adding an additional complexing agent. In this work, 9 mg of the synthesised adsorbent (NH2-UiO-66 (Zr) MOF) was dispersed into 6 mL of sample solution containing Cu(II) and Cd(II) ions. Then, a synthesised deep eutectic solvent was used to elute and desorb the analytes from the surface of the sorbent. The effect of important parameters such as sorbent amount, sample solution volume, extraction time, elution solvent type and volume, desorption time, pH and salt addition on the extraction efficiency of the method was investigated. The developed procedure had linear ranges of 1–100 and 0.5–150 µg L−1 with the limits of detection of 0.37 and 0.19 µg L−1, for Cu(II) and Cd(II) ions, respectively, with flame atomic absorption spectrometry determination. To study the validity of the procedure, the concentration of the analytes was determined in a certified reference material (SPS-WW2) by the proposed method. Finally, the proposed procedure was used for the determination of the concentrations of Cu(II) and Cd(II) ions in different fruit juice and water samples.