Carbon Dioxide

Carbon Dioxide

Carbon dioxide easily diffuses into water forming carbonic acid (H2CO3). In water carbonic acid quickly dissociates into hydrogen ions (H+) and bicarbonate ions (HCO3). These ions increase the conductivity and decrease the resistivity and pH of the water.

Lakes and rivers contain carbon dioxide naturally at concentrations of less than 10 mg/L. However, stagnant or polluted water can generate large amounts of carbon dioxide due to organic or mineral decomposition. Higher amounts of carbon dioxide can make the water corrosive and toxic to aquatic organisms. Monitoring carbon dioxide levels is also critical in the man-made environment. Carbon dioxide is added to drinking water during the final stages of the purification process. In water softening systems, a delicate balance of carbon dioxide must be maintained to prevent corrosion or encrustation of pipes and storage tanks.

Hanna Instruments offers a variety of methods to measure carbon dioxide in water, soft drinks, and wine. Products include portable and benchtop pH/ISE meters that can use a gas membrane carbon dioxide Ion-Selective Electrode (ISE) for direct measurement. In addition, carbon dioxide levels can be measured with a chemical test kit that is based on a phenolphthalein titration. The phenolphthalein is first added to the sample and then titrated with a sodium hydroxide standard solution until the sample changes color at the endpoint pH of 8.3.


Benchtop pH/ISE meters include a two channel option in which a pH probe can be connected to one channel and the carbon dioxide ISE to the other. The benchtop meters have the ion charge and formula weight pre-programmed for use with the carbon dioxide ISE. The benchtop meters also have incremental methods pre-programmed including the known addition, known subtraction, analyte addition and analyte subtraction methods


Solutions for carbon dioxide measurement include ISE standards and ISA for calibration and measurement.


Accessories include magnetic stirrers to ensure adequate mixing when using an ISE and the spare parts for the carbon dioxide ISE.

Chemical Test Kits

Several chemical test kits are available for measuring carbon dioxide from single parameter test kits to multiparameter test kit for water quality.