Diluent buffer for the binding agent. Suitable for use with the PDE assay kit (BPS Bioscience, Cat. #60300) for the study of phosphodiesterases which can hydrolyze cGMP (PDEs 1, 2, 3, 5, 6, 9, 10, and 11). Not suitable with cAMP-selective PDEs (4, 7, 8).