Kinetic rates of receptor-ligand, protein-protein, antigen-antigen interactions can be readily followed using optical biosensors. However care must be taken to ensure datasets report specific binding events since solid phase chemistries used to couple targets (eg., silica/quartz) afford ample contact surfaces for biologicals. Buffer effects like pH/salt/temperature provide strong influences on 'non-specific' protein associations so a variety of validation controls must be implemented to ensure biosensor signals represent 'true' interactions with targets of interest. For example, it is possible to determine binding specificities by measuring kinetic interactions with a variety of closely related target structures (eg., antibodies with peptides having a similar amino acid composition but differing sequences). Biosensors are mass driven analytical instruments, often requiring saturating concentrations of analyte, albeit often in very crude form (eg., antisera), to demonstrate good binding signals. High affinity interactions are quickly discerned as those having rapid association rates and conversely slow dissociation rates. Binding stoichiometries and changes in kinetic affinities are most commonly used to characterize the efficacy of biologicals following purification and/or formulation.