Association Constant - A reaction between antibody and its determinant which comprises a measure of affinity. Immunoassay - A qualitative or quantitative assay method based on the measure of interplay of excessive affinity antibody with antigen used to identify and quantify proteins. High Performance Liquid Chromatography (HPLC) - An instrumental separation approach used to characterize or to determine the purity of a BDP by passing the product (or its part peptides or amino acids supplier USA acids) in liquid kind over a chromatographic column containing a stable support matrix.