Determination of Carbon Dioxide and Bicarbonate

The determination of carbon dioxide is an important analytical problem, especially when low concentrations are to be measured. Ion-exclusion chromatography provides a convenient way to determine carbon dioxide, or its form in solution which is molecular carbonic acid. The separation column is packed with a cation exchange resin in the form so that salts are converted to the corresponding acid. Ionized acids pass rapidly through the column while molecular acids are held up to varying degrees. A conductivity detector is commonly used. 

Unfortunately, carbonic acid is a very weak acid (p/f = 6.4) and the conductance of the carbonic acid peak consequently is very low. In order to obtain a more sensitive detection, Tanaka and Fritz inserted a cation-exchange column in the form between the cation-exchange column and the detector [10]. Its purpose is to convert 

With this column in place a standard sample of 1.0 mM bicarbonate gave a conductance of 0.504 pS, which was approximately 5.5 times greater than that obtained with no enhancement column. 

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