The product, hippuric acid, can be extracted and quantified by its absorbance. Alternatively, it can be measured by using liquid chromatography with UV detection for separation and measurement without having to do an extraction.

Here is a protocol for the extraction method:

https://www.sigmaaldrich.com/content/dam/sigma-aldrich/docs/Sigma/Enzyme_Assay/a6778enz.pdf

Thank you Adam B Shapiro

So if i get 55% inhibition during ACE enzyme assay, what does it mean and correlate with substrate HHL and product hipuric acid

Kindly check https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5414448/

Kindly check https://pubmed.ncbi.nlm.nih.gov/16476177/

Also check https://www.sciencedirect.com/science/article/pii/S0014579303013553