Typical titration curve of purified anti CNP in a competitive ELISA with this antibody. Procedure: antibody was applied to goat anti rabbit IgG-coated microtiter plate. tracer or tracer / antigen mixture was added, developed with streptavidin-HRPO and TMB as substrate for HRPO. Red curve: titration of antibody with CNP tracer (biotinylated peptide and streptavidin-HRPO). Blue curve: inhibition of tracer by antigen, showing affinity of antibody for CNP and tracer.