Chromatographic Analysis of Chloramines using Electrochemical Detection
This report was produced for the Urban Water Research Association of Australia, a now discontinued research program.
Report No UWRAA 11
The introduction of chloramination procedures for the disinfection of potable water supplies requires the associated development of accurate laboratory techniques to monitor the levels of these compounds.
Present methods used routinely to analyse chloramines are prone to a broad range of interferences, are difficult to automate, and require the pH to be altered from the natural value of the sample. This gives rise to uncertainty in the accuracy of speciation data.
We report here the development and evaluation of a method using HPLC with electrochemical detection (HPLC/EC). It gives an order of magnitude improvement in sensitivity over existing methods using HPLC with spectropotometric detection. The working determination limits for real samples were 0.1 mg/L formonochloramine and >0.03 mg/L for dichloramine.
The major problems encountered in HPLC/EC determination of chloramines are:
1. There are no readily available standards, so the method must be calibrated against another accepted method.
2. The electrochemical cell requires regular disassembly to clean the electrode.
3. It takes 1-2hours to achieve a stable background current in the electrochemical detector after it is first connected.
These problems need to be addressed before the method could be introduced as a routine laboratory test.