Mouse anti-Virus HRH4 monoclonal antibody for cI-ELISA. Sudan I (also commonly known as CI Solvent Yellow 14 and Solvent Orange R), is a lysochrome, a diazo-conjugate dye with the chemical formula of 1-phenylazo-2-naphthol. Sudan I is a powdered substance with an orange-red appearance. The additive is mainly used to colour waxes, oils, petrol, solvents and polishes. Sudan I has also been adopted for colouring various foodstuffs, including particular brands of curry powder and chili powder, although the use of Sudan I in foods is now banned in many countries, because Sudan I, Sudan III, and Sudan IV have been classified as category 3 carcinogens (not classifiable as to its carcinogenicity to humans) by the International Agency for Research on Cancer.