Optimised ligand exchange solvent extraction methodology for the determination of labile and inert forms of copper in environmental samples

The dataset is associated with the publication “Optimised ligand exchange solvent extraction methodology for the determination of labile and inert forms of copper in environmental samples”. It comprises the data used to generate the figures presented in the main manuscript as well as in the Supporting Information. The dataset includes absorbance measurements at 346 nm of the Cu–SA bis-complex recorded during titration with EDTA, which were used to determine the conditional stability constant of the Cu(II)–SA bis-complex by a spectroscopic approach. In addition, voltammograms of model solutions are provided: (1) 10 nM Cu(II) in 0.01 M carbonate buffer containing 1, 10, and 100 µM salicylaldoxime (SA), and (2) 100 nM Cu(II) in 0.01 M carbonate buffer containing 1, 10, and 100 µM SA. All model solutions were extracted with 90 mL toluene, back-extracted with suprapure nitric acid, and analysed electrochemically. Finally, the dataset contains data on extracted copper obtained using different concentrations of salicylaldoxime from three sampling campaigns conducted in June 2025, September 2025, and November 2025.