Chloronaphthol (4-CN) is a peroxidase substrate used for chromogenic detection of HRP in immunoblotting and immunohistochemical applications. This product is less sensitive than other precipitating substrates, but the distinct blue to blue-purple precipitate photographs well and can be useful in double-staining applications. The coloured product is soluble in alcohol and xylenes, but is not soluble in aqueous buffers. The 1-Step Chloronaphthol is supplied ready to use.