Compositions and methods for simultaneous inactivation of alkaline phosphatase and peroxidase enzymes during automated multiplex tissue staining assays

A method of inactivating one or more enzymes in a biological sample comprising applying between about 50 μL to about 200 μL of an enzyme inactivation composition comprising a polycarboxylic acid, a peroxide, and a preservative to the biological sample, wherein the enzyme inactivation composition has a pH ranging from between about 1 to about 3, the biological sample comprising one or more reagent or endogenous enzymes, and wherein at least one of the enzyme inactivation composition or the biological sample is maintained at a temperature ranging from between about 25° C. to about 50° C. for a time period ranging from between about 4 minutes to about 16 minutes.