Product Short Description: NNNN TETRAMETHYL p PHENYLENEDIAMINE DIHYDROCHLORIDE Product Description: N,N,N′,N′-tetramethyl-p-phenylenediamine dihydrochloride (TMPD) is an oxidizable compound that serves as a reducing co-substrate for heme peroxidases. It is also used as a test reagent in microbiology for the classification of cytochrome oxidase positive aerobic microorganisms.