For detailed instructions see for example https://www.sigmaaldrich.com/technical-documents/protocols/biology/enzymatic-assay-of-peroxidase-abts-as-substrate.html.

For details on how to perform standard calculations in biochemistry, see the old but still relevant

@BOOK{Seg-76,

AUTHOR = {Segel, I.H.},

TITLE = {Biochemical Calculations: How to Solve Mathematical Problems in General Biochemistry},

YEAR = {1976},

PUBLISHER = {Wiley},

address = {London, New York, Sydney, Toronto},

ISBN = {9780471774211},

url = {https://de.scribd.com/doc/61976550/Biochemical-Calculations-Segel-2a},

edition = {2},

}

The instructions are clear, easy to follow. But the pdf file is clearer and easier to read including equations and so on. Avaiable from

https://www.sigmaaldrich.com/content/dam/sigma-aldrich/docs/Sigma/Enzyme_Assay/p6782enz.pdf

Sushma Chauhan Agreed with Engelbert & Richard that protocol is useful in calculating peroxidase activity. Hope it was useful for you?

https://www.sigmaaldrich.com/content/dam/sigma-aldrich/docs/Sigma/Enzyme_Assay/p6782enz.pdf