SELECTIVE DETERMINATION OF CADMIUM IN WATER USING A CHROMOGENIC CROWN-ETHER IN A MIXED MICELLAR SOLUTION

The chromogenic crown either ydroxy-5-nitrobenzyl)-4,13-diazadibenzo-1 8-crown-6 (CCE) has been solubilized in a mixed micellar solution of s odium dodecyl sulfate and cetyl pyridinium chloride and tested for the selective determination of heavy metals ions. The optical properties, acid-base equilibria, and metal ion binding capabilities of the micel lar-solubilized CCE for Ba(II), Ca(II), Cd(II), Cu(II), Hg(II), Pb(II) , and Sr(II) are reported. Results show that the micellar-solubilized CCE binds Hg(II) similar to Cd(II) > Ca(II) > Sr(II), whereas the pres ence of Pb(II) and Ba(II) leads to precipitate formation. There was no detectable binding with Cu(II). Based on these results, a spectrophot ometric determination for Cd(II) that utilizes chloride ions to mask H g(II) has been devised and evaluated.