EVALUATION OF ACOUSTIC-EMISSION AS A MEANS FOR CARBONATE DETERMINATION

A method is described for the determination of total carbonate by mean s of acoustic emission. Acoustic signals are generated from effervesce nce of carbon dioxide when aqueous samples containing carbonate or hyd rogencarbonate are acidified. Two approaches are evaluated. The first involves direct mixing of carbonate and acid streams in a flow system. Detection limits around 0.1 M are observed with this arrangement. In the second approach, the flow system is used to preconcentrate the car bonate species onto an anion exchange column prior to acidification. L imits of detection below 3.5 mu mol of carbonate are achieved with thi s method (1 mM hydrogencarbonate at a flow rate of 1 ml min(-1) for 3. 5 min). Sensitivity is found to be optimum when a glass frit is placed in-line and the acid now is opposite to that of the carbonate. Calibr ation curves are nonlinear for both the direct and preconcentration me thods. Limitations of the proposed methods are discussed.