SYSTEM FOR MEASURING CARBON DIOXIDE CONCENTRATION IN WATER AND METHOD THEREOF

摘要

The purpose of this object is to provide a system for measuring carbon dioxide concentration in water by which a decrease in the measurement accuracy caused by the deterioration of a pH indicator can be corrected. A system for measuring carbon dioxide concentration (1) which comprises a deterioration determining unit (31) whereby a change rate ?A0 in the isosbestic point absorbance A0 is measured and, when the change rate ?A0 becomes equal to or lower than a predetermined decrease rate, it is determined that the pH indicator solution is deteriorated. After the determination of the deterioration of the pH indicator solution by the deterioration determining unit (31), a pH value calculating unit (27) calculates the pH value of the pH indicator solution in accordance with a correction pH operational expression by which the deterioration is corrected with the use of the change rate ?A0 in the isosbestic absorbance A0.