[Enzyme-immunological tests: determination of the activity of peroxidase with the aid of the "Trinder reagent" (author's transl)].

Most of the currently used enzyme-immunological tests employ horse radish peroxidase as a marker enzyme. A new method is described for the determination of extremely small quantities of peroxidase. This largely prevents the inactivation of the peroxidase by H2O2 and thereby permits a much longer incubation time. In the presence of 25 mmol/l phenol, 2 mmol/l 4-amino-antipyrin and 0.8 mmol/l H2O2, peroxidase catalyses the formation of a red quinonimine, whose increase in adsorption is directly proportional to the enzyme concentration.