Permanganate index in water – Fully automated determination according to GB/T 11892

The permanganate index (PMI) is a sum parameter that indicates the total load of oxidizable organic and inorganic matter in water. The substances concerned are mainly humic materials/acids that are formed primarily when dead organic material in the soil is further broken down and transformed in this process. As it is an indicator of the water quality, testing of the PMI for drinking water is obligatory in many countries.

For the determination, it is necessary to heat the treated water sample to 95 °C and higher for a stipulated time. Afterwards, the amount of permanganate, which reacted with the sample, is determined titrimetrically. This sample preparation step requires considerable manual effort. In this Application Note, a fully automated procedure for the determination of the PMI according to GB/T 11892 including all sample preparation steps is described. The gains in productivity as a result of reduced manual workload are considerable.