An embodiment provides a method for measuring peracetic acid concentration in an aqueous solution, including: combining, in a reactive solution, 4-(methylthio)aniline and at least one reactive species to produce a chromophore, wherein the at least one reactive species comprises a chromotropic acid disodium salt; placing the chromophore in an aqueous solution, wherein the aqueous solution comprises peracetic acid, wherein peracetic acid within the aqueous solution reacts with the chromophore; and measuring a concentration of peracetic acid within the aqueous solution, wherein the measuring comprises quantifying a colorimetric change of the aqueous solution caused by the peracetic acid reacting with the chromophore. Other embodiments are described and claimed.