Streptavidin-coated solid phases serve as reliable binding surfaces for all types of biotinylated molecules. Numerous ligands can be biotinylated simply and due to the low molecular weight of biotin (244 Da) the functionality of the molecules is normally not impaired.Thus streptavidin-coated solid phases make it possible to rapidly isolate, determine and quantify components from a reaction mixture. By immobilising the biotinylated substance, it is also possible to reproduce complete reaction chains on a streptavidin solid phase, e.g. enzyme immunoassays,enzyme activity assays, DNA hybridisation techniques,quantification of PCR products and receptor/ligand studies. The high-purity streptavidin is bound to the plate surface in a uniform and stable layer. The coefficient of variation from well to well is under 5 % for 96 well microplates and under 8 % for 384 well microplates. The streptavidin solid phase is treated with an additional blocking step in order to minimise any unspecific binding, therefore, „pre-blocking” of plates is not necessary. The high stability of the coating and the high affinity between streptavidin and biotin enables unusually stringent washing conditions, which have a positive effect on the signal-to-noise ratio of the measurement.