The HBS-EP Buffer (HEPES Buffered Saline with EDTA and Surfactant P20) is a variant of HEPES Buffered Saline, useful in SPR (Surface Plasmon Resonance) protocols. This reagent is formulated at a pH of 7.4 and can be used to prime in-unit pumps within SPR devices. Serving as both a running and binding buffer in such protocols, the HBS-EP solution is useful in assessing binding characteristic and biochemical dynamics between analytes. This solution employs a lower concentration of Surfactant P20 than HBS-EP+ solutions.