Potassium metabisulfite, K2S2O5, also known as potassium pyrosulfite, is a white crystalline powder with a pungent odour. It is mainly used as an antioxidant or chemical sterilant. As a disulfite, it is chemically very similar to sodium metabisulfite, with which it is sometimes used interchangeably.
Potassium metabisulfite is used in the textile industry for dyeing and cotton printing. Potassium metabisulfite is sometimes used to precipitate gold from solution in aqua regia (as an alternative to sodium sulfite). It is a component of certain photographic developers and solutions used in photographic fixing.
Potassium metabisulfite has been shown to produce limited chromosomal aberrations, sister chromatid exchange, and micronucleus formation in human lymphocytes in tissue culture
