The Ostase? EIA assay is a solid phase, monoclonal antibody immunoenzymetric assay. Samples containing BAP are reacted with a solution containing a biotin-labeled, BAP-specific monoclonal antibody. The reaction takes place in plastic well strips (solid phase) coated with streptavidin and enclosed in a plastic frame. Following the formation of a solid phase/capture antibody/BAP complex, the microplate is washed to remove unbound BAP and is then incubated with an enzyme substrate. The amount of substrate turnover is determined colorimetrically by measuring the absorbance of the quenched reaction at 405 nm in a microplate reader. The absorbance is proportional to the concentration of BAP present in the test sample. The calculation of BAP concentration in the sample is based on concurrent testing of BAP calibrators and Zero Calibrator/Diluent.