“…Commercial extractants containing phosphine oxides [20,21], amines [22], thiophosphinic acids [23], and calixarene derivatives [24] were investigated with respect to Au(III). Spectrophotometric determination of gold in water and ore with 2-carboxyl-1-naphthalthiorhodanine was studied by Chen et al [25]. Three derivatives of dibutylphosphonic acid, , 0 -bis(dibutylphosphonatol)-l,3-xylene and bis(dibutylphosphonato)alkanes, commonly known as the tetrabutyl 1,3-xylylenediphosphonate (TBmXDP) and tetrabutyl alkylenediphosphonates (TBADP), respectively, were synthesized by Chowdhury and Kamata [26] for use in solvent extraction of precious metals, especially Au(III) extraction from hydrochloric acid medium.…”