It is primarily used as a chromogenic reagent in analytical chemistry for colorimetric detection of phenols hydrogen peroxide and oxidase activity in enzymatic assays.

Its main purpose is to undergo oxidative coupling with phenols in the presence of oxidants (e.g. HOenzyme) to form intensely colored quinoneimine dyes measurable at 500 nm for quantitative analysis.

4-Aminoantipyrin is a yellow crystalline solid derivative of antipyrine featuring a pyrazolone ring with methyl groups at positions 2 and 3 a phenyl at N1 a keto at C5 and an amino group at C4 with molecular weight 203.24 gmol and melting point 105110C.