An inventory of the European market showed that 12 automatic nitrate analyzers were available using measuring techniques based on ion specific electrodes, colorimetry and UV absorption.
Among these analyzers the following six - Data Link, Dr Lange, M.E, Phox, Polymetron, Process Styrning - were put through two series of tests:
- metrological characteristics of the instruments,
- behaviour in waste water and comparison with analyses of samples in laboratory.
The metrological quality of all the analyzers is sufficient, but all the ion specific electrode analyzers showed contamination and rapid drift when used in waste water.
The others show greater resistance. UV absorption systems are simpler and quicker to use. They are also less demanding with regard to sample conditioning than colorimetric apparatus.