SPECTROPHOTOMETRIC DETERMINATION OF CADMIUM(II) WITH DITHIZONE AND 1,10-PHENANTHROLINE

Cadmium(II) has been quantitatively separated from zinc(II) by an ion-pair extraction system. An ion-pair consisting of cadmium(II) and 1,10-phenanthroline (phen) was found to be preferentially extracted into chloroform from an aqeuous chloride solution containing zinc(II). The extracted species in chloroform reacted with dithizone (H//2Dz) to give the reddish mixed complex Cd(HDz)//2(phen) having an absorption maximum at approximately 505 nm. The resulting calibration curve obeys Beer's law, the Sandell sensitivity being 0. 0013 mu g cm** minus **2. The effect of diverse ions has been examined, and a new highly selective method for the spectrophotometric determination of trace amounts of cadmium in metallic zinc established.