Hgcl2

The Citrus clementina peels were collected from the Dalibor Ujević family farm (Opuzen, Croatia) and were washed with water several times before use. Amino acids L-glycine and L-arginine were purchased from Merck, Germany, and Sigma–Aldrich, USA. Ascorbic acid (Gram Mol, Croatia) and different inorganic salts used for selectivity measurements were as follows: FeCl₃ × 6H₂O (VWR International, USA), MgCl₃ × 6H₂O (T.T.T., Croatia), CaCl₂ × 2H₂O (BDH Prolabo, UK), KCl, NaCl (Gram Mol, Croatia), CuCl₂ x 2H₂O (Kemika, Croatia), AlCl₃ x 6H₂O (Brend Kraft, Germany), HgCl₂ (VWR International, USA), and MnCl₂ x 4H₂O (Sigma–Aldrich, St. Louis, MO, USA). The quinine sulfate and DPPH assay (2,2′-diphenyl-1-picrylhydrazyl) were supplied by Merck, Germany. The chemicals and solvents, such as ethanol, methanol, dimethyl sulfoxide (DMSO), acetone, sulfuric acid, acetic acid, and hydrochloric acid, were purchased by Merck, Germany, while NaOH pellets were obtained by Gram Mol, Croatia. Milli-Q pure water obtained by the Milli-Q Millipore system (conductivity ≤ 0.054 μS/cm) was used throughout the samples preparation and analytical measurements. The sample purification was carried out using dialysis membrane Spectra/Por 7 (MWCO 1kDa) supplied by Spectrum Labs (Rancho Dominguez, CA, USA).
All reagents and chemicals were of analytical grade and were used further without purification.