A dithizone-anchored silica gel surface, {SiO2}@DZ for the selective sample cleanup of Gd(iii) amidst Fe(iii), Th(iv), and Ce(iv) employing ion pair complexation

Sorption–desorption equilibration, {extractor-HOMO}:{H₃O}⁺+ {metal-species}ⁿ⁺⇄ {extractor-HOMO}:{metal-species}ⁿ⁺+ {H₃O}⁺, an eventual ion-pair complexation controlled by {H₃O}⁺.