Is immunoprecipitation quantitative?

Yes, immunoprecipitation is quantitative.

Immunoprecipitation (IP) is used to separate proteins that are bound to a specific antibody from the rest of a sample. the goal of immunoprecipitation is to isolate just enough protein to be able to measure it by western blotting or other semi-quantitative or quantitative assay methods. Usually treated and untreated samples are compared to assess the relative amount of the protein of interest.