INT is a Tetrazolium derivative, that on reduction produces a red formazan dye that can be used for quantitative redox assays. INT have been used in cytology since the 1950s to detect reducing cell components and later to label metabolically active cells. Also, INT has been adapted in aquatic samples for the in vitro electron transport system (ETS) method, which allows the plankton respiration to be measured with higher sensitivity. INT have been shown to inhibit bacterial growth.