IMPROVEMENT OF THE EXTRACTION-SPECTROPHOTOMETRIC DETERMINATION OF TOTAL CARBONATE USING URANYL QUINOLIN-8-OLATE AND BENZYLTRIBUTYLAMMONIUM BROMIDE

An indirect spectrophotometric determination of carbonate is proposed. Dilute chloroform solutions of uranyl quinolin-8-olate are shaken wit h aqueous solutions of anion. The decoloration produced by ligand exch ange varies linearly with the anion concentration. The addition of an ethanolic solution of benzyltributylammonium bromide to the organic so lution instead of an excess of quinolin-8-ol improves the method. Diff erent variables (pH, shaking time, ionic medium) were optimized. Carbo nate concentration can be determined over the range 10-40 mu g ml(-1), showing a linear dependence, giving a precision of 2.4% for 30 mu g m l(-1) of carbonate in the aqueous phase. The tolerance levels of forei gn ions are increased. Analysis of carbonate in mineral and sea waters and pharmaceutical samples was performed with success.