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Sudan III(From Wikipedia)
Synonyms:   1-[4-(Phenylazo)phenylazo]-2-naphthol; C.I. 26100; Solvent Red 23;   Sudan III  (http://www.lookchem.com/cas-85/85-86-

9.html)solution; 1-(4-(phenylazo)phenylazo)-2-naphthol;  

Sudan Red  (http://www.lookchem.com/cas-311/3118-97-6.html) (chromatographic standard); Sudan Red 
CAS RN.:   85-86-9 
EINECS:   201-638-4 
Molecular Weight:   352.39 
Molecular Formula:   C22H16N4O 
Sudan III is a lysochrome (fat-soluble dye) diazo dye used for staining of triglycerides in frozen sections, and some protein bound lipids

and lipoproteins on paraffin sections. It has the appearance of reddish brown crystals and a maximum absorption at 507(304) nm.Sudan

III is a dye used for Sudan staining. Similar dyes include Oil Red O, Sudan IV, and Sudan Black B.
Its risk and safety phrases are S22-S24/S25.
Its other names are Sudan Red BK, Fat Ponceau G,   Cerasin Red   (http://www.lookchem.com/cas-85/85-86-9.html), C.I.

26100, Solvent Red 23, Sudan Red, Sudan Red III, Sudan V, Sudan Red B, Sudan G, Scarlet B, and Tony Red.
In industry, it is used to color nonpolar substances like oils, fats, waxes, greases, various hydrocarbon products, and acrylic emulsions. :D