Pierce™ CN/DAB Substrate Kit is for chromogenic detection of horseradish peroxidase in immunohistochemistry and immunoblotting applications. The formed product is a black precipitate that photographs well and is useful in double staining applications. The coloured product is soluble in xylenes but not soluble in aqueous buffer such as Tris or phosphate. This combination of DAB and CN has a synergistic effect that results in greater sensitivity than either reagent alone.