Back-titration method for the determination of free, dissolved carbon dioxide

3 Back-titration method for the determination of free, dissolved carbon dioxide  

The water sample containing carbonic acid is added to excess sodium hydroxide solution, and sodium carbonate is formed. During back-titration 

The method is suitable for the determination of free, dissolved carbon dioxide over a very broad concentration range (approximately 100 to 3000 mg/1). It may be used for the analysis of natural waters which contain considerable quantities of calcium and magnesium ions in addition to iron (II) ions. The method is intended primarily as a field method. It allows the determination of CO2 with an average error of +2 to 3 %. 

Interference due to alkaline-earth ions and heavy metal ions can be eliminated by the addition of a suitable masking agent. According to an investi- 

When taking the sample for titration, care must be taken to avoid CO2 losses. For this reason, the sampling containers must be filled to overflowing from the base upwards at the sampling point. Submerge the pipette in order to extract the sample and introduce into the flask containing reagents. 

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