The method describes how to determine the manganese content of water through oxidation to permanganate.
Water intended for use as an ingredient in the production of beer (brewing liquor) or other foods
Manganese found in natural waters is often accompanied by iron, both usually as hydrogen carbonates. Manganese generally occurs only in low concentrations. Similar to iron ions, manganese can form deposits and accumulate as sediment in piping (particularly in the presence of manganese bacteria); demanganization may be necessary in such cases. Furthermore, manganese supports the growth of beer-spoiling pediococci.
Manganese ions are catalytically oxidized into purple-colored permanganate ions. The purple color of the solution is determined using a comparator (or photometrically):
Mn2+ + 12 H2O → MnO4- + 8 H3O+ + 5 e-