Analytical Sciences

Analysis of Carbonic Acid in Water Samples by Ion-Exclusion Chromatography with Pure Water as Eluent

Hui FAN,* Mingyu DING,* Kazuhiko TANAKA,** and Wenzhi HU***

*Department of Chemistry, Tsinghua University, Beijing, 100084, China
**National Institute of Advanced Industrial Science and Technology at Seto, 110 Nishiibara-cho, Seto, Aichi 489-0884, Japan
***Division of Chemistry, Graduate School of Science, Hokkaido University, Sapporo 060-0810, Japan

A simple, sensitive and rapid ion-exclusion chromatographic method for the simultaneous separation of carbonic acid and short chain organic acids (formic acid, acetic acid, and propionic acid) has been developed. A weakly acidic cation exchange resin column TSKgel OApak-A was used for the separation; pure water, owing to its lower background conductance, was employed as eluent in order to obtain high detection sensitivity. A good separation of these weak acids was achieved in 16 min. The linear range of the peak area calibration curve for carbonic acid was from 3.0 mg/L to 500 mg/L. The conductivity detection limit calculated at S/N = 3 was 0.084 mg/L for carbonic acid. The method developed in this work was successfully applied to the determination of carbonic acid in several environmental water samples without any pretreatment.

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