SOLID-PHASE EXTRACTION OF METAL-IONS USING IMMOBILIZED CHELATING CALIXARENE TETRAHYDROXAMATES

The synthetic macrocycles, known as calixarenes, have been shown to po ssess high ionophoric selectivity and form inclusion complexes with ma ny ions. A tetrameric calixarene bearing hydroxamic acid functional gr oups was synthesised and supported on octadecylsilica and XAD-4 resin. When loaded with Fe(III), V(V) and Cu(II), the materials display the characteristic visible absorption spectra associated with hydroxamate coordination. The chemical bonding of the calixarene tetrahydroxamic a cid to silica particles was also carried out using the triethoxysilane derivative of the p-allylcalix[4]arene hydroxamic acid. When packed i nto small cartridges, these materials are used for the solid phase ext raction of transition metal ions from aqueous solution. Metal uptake p rofiles as a function of pH are presented for Fe(III), Co(II), Pb(II), Cd(II), Mn(II), Ni(II), Zn(II) and Cu(II). The quantitative trace enr ichment of Cu(II), Zn(II) and Mn(II) from water samples prior to ion c hromatographic analysis is demonstrated.