Summary of representative hydrophilic ligands from their extraction performances and extraction experimental conditions. Data in blue and yellow shaded areas were based on hydrophilic ligands with alkyl-chain-skeleton and multiple-aromatic-skeleton, respectively. The rest were from hydrophilic ligands with simple-aromatic-skeleton. The dashed arrows in the yellow area indicated the decrease of the extraction performances of the same ligand at different acidity. The experimental conditions were summarized in Table 1.