Fast Red is a widely used chromogen for immunohistochemical staining. When in the presence of alkaline phosphatase (AP) enzyme, Vulcan Fast Red produces a bright fuchsin-red precipitate that is insoluble in organic solvents and can be coverslipped with a permanent mounting media. This product is available in a stable two-component system, consisting of Vulcan Fast Red Chromogen and Vulcan Buffer. When using an alkaline phosphatase system, tris buffer (pH 7.6) should be used as a rinsing buffer. PBS should never be used! Phosphates act as a competitive inhibitor to alkaline phosphatase enzymes.For optimum performance, use IMMUNOCARE TBS Wash Buffer with AP activator or TBS Wash Buffer 20X.