Abstract: Improved test compositions, devices and methods are provided for detecting peroxidatively active substances in body fluids, excreta and the like. In the type of test compositions including an indicator capable of being oxidized in the presence of a peroxidatively active substance to provide a color change, an oxidizing agent effective to oxidize said indicator, and a potentiating agent, the improvement comprises the use as said potentiating agent of an acid salt or adduct of a compound selected from the class of compounds of the general formula ##SPC1##Wherein R.sub.1 is hydrogen, lower alkyl, hydroxy or thiophenyl; R.sub.2 is hydrogen or lower alkyl; R.sub.3 is hydrogen or lower alkyl; R.sub.4 is hydrogen, carboxy, lower alkyl or lower alkoxy; and R.sub.5 is hydrogen or lower alkyl.