Notes on the determination of total and residual chlorine in drinking and process water using an automated ProcessLab system from Metrohm
At pH <4 chlorine, hypochlorite and chloramine release iodine from potassium iodide by oxidation.
The reactions take place strictly stoichiometrically.
The released iodine can be titrated with phenylarsine oxide.
Potentiometry (combined platinum electrode) or biamperometry (double Pt electrode) is used for endpoint indication.
In contrast, if the titration is carried out at approx pH10 then only the free chlorine is determined.
The results are given in mg/l chlorine, as free chlorine is the main oxidant contained in the sample.
This method can be used to determine a chlorine content <0.5mg/l without any problems.
For the determination of the chlorine content an automated ProcessLab system is used.
Liquid handling of the needed buffers is done using the buret and pumps which ProcessLab provides.
Sample identification cab be done with a barcode reader.
This system is very flexible and can be adapted very easily to any specific needs.
If necessary an additional reagent cabinet is available and can be placed directly under ProcessLab.
It has sufficient space for all reagents and makes ProcessLab even more comfortable.
