Determination of total carbonate-carbon in river water by ion chromatography with photometric detection

Abstract

Determination of total carbonate-carbon in river water was achieved by ion chromatography with an ultraviolet photometric detector and an anion exchange column(TSK gel IC-Anion PW, 4.6 mm i.d. × 50 mm). Trimellitate (1,2,4-benzenetricarboxylate, 4 ×10-4 M) solution(pH 7.5) was used as an eluent. Ten microliters of sample solution was injected and decrease in absorbance of the trimellitate eluent at 270 nm was detected. Calcium and magnesium ions interfere with the determination of total carbonate-carbon. These could be removed completely by passing the sample solution through a cation exchange-type pretreatment cartridge column (sodium type). The expelled trimellitate ion from the column by anions (chloride, sulfate and nitrate ions) in sample solution decreased the peak height of hydrogen carbonate ion. This interference could be corrected by using the summation of peak areas of coexisting anions. By the proposed method, total carbonate-carbon in river water was determined. For total carbonate-carbon, the results were in good agreement with the values obtained by FIA. © 1987, The Japan Society for Analytical Chemistry. All rights reserved.