Peracetic acid is often used in bottling plants as a terminal disinfectant. There are several methods of measuring peracetic acid concentration and these are reviewed here:
A titration technique involves the use of three different chemicals and relies on detecting a colour change, followed by a calculation.
The simplest method utilises test strips which change colour on immersion in the test solution. The colour is related to the concentration in mg/L.
Conductivity measurement is not reliable and requires addition of a tracer (nitric acid) to the peracetic acid.
A recent development has seen the emergence of peracetic acid sensitive electrodes. The test solution is made to flow through a cell where the electrodes produce a signal related to concentration. The whole system can be made automatic, so that top up occurs as the solution becomes depleted.