1992 Volume 8 Issue 5 Pages 605-608
A "pH scanning technique" was introduced for the liquid-liquid extraction of metal chelates by high-speed stirring. The increase of pH in the aqueous phase containing phosphoric, boric and acetic acids as pH buffer reagents was controlled by addition of a 5M NaOH solution at the rate of 0.9ml/min. The relationship between pH change in the aqueous phase and the addition time of the NaOH solution was almost linear in the range of pH 2.5-11. The absorbance of metal complexes extracted into chloroform phase was recorded continuously after the separation of organic phase from the mixture of two liquids by use of a Teflon phase separator under the conditions of high-speed stirring. By the present method, copper(II), cobalt(II) and indium(III) were simultaneously determined in the range of 0.1-60μg with 8-quinolinol. The advantage of the present method was the separation of some metals having rapid-extraction rates from other metals having slower rates.