Sudan II is a lysochrome

Lysochrome

A lysochrome is a soluble dye used for biochemical staining of triglycerides, fatty acids, and lipoproteins. Lysochromes such as Sudan IV bind to the lipid in a substrate and show up as colored regions. The dye does not stick to any other substrates, so a quantification or qualification of lipid...

 (fat-soluble dye) azo dye used for staining

Staining (biology)

Staining is an auxiliary technique used in microscopy to enhance contrast in the microscopic image. Stains and dyes are frequently used in biology and medicine to highlight structures in biological tissues for viewing, often with the aid of different microscopes...

 of triglycerides in frozen sections, and some protein bound lipids and lipoproteins on paraffin

Paraffin

In chemistry, paraffin is a term that can be used synonymously with "alkane", indicating hydrocarbons with the general formula CnH2n+2. Paraffin wax refers to a mixture of alkanes that falls within the 20 ≤ n ≤ 40 range; they are found in the solid state at room temperature and begin to enter the...

 sections. It has the appearance of red powder with melting point 156-158 °C and maximum absorption at 493(420) nm.

Other names

Its other names are Solvent Orange 7, C.I. Solvent Orange 7, and C.I. 12140. It is also known as: A.F. red No. 5, Aizen food red No. 5, Brasilazina oil scarlet 6G, Brilliant oil scarlet B, Calco oil scarlet BL, Ceres Orange RR, Cerisol scarlet G, Cerotinscharlach G, Ext. D and C red No. 14, Extract D and C red No. 14, Fast oil Orange II, Fat scarlet 2G, FD and C red 32, FettOrange B, Grasan Orange 3R, Lacquer Orange VR, Motirot G, Oil Orange KB, Oil red GRO, Orange oil KB, Orange RR, Ponceau à l'huile, Pyronalrot R, Red B, Red No. 5, Resin scarlet 2R, Resoform Orange R, Rot B, Somalia Orange 2R, Soudan II, Sudan AX, Sudan Orange, Sudan red, Sudan scarlet 6G, Sudan X, Waxakol vermilion L.

Uses

In industry, it is used to color nonpolar substances like oil

Oil

An oil is any substance that is liquid at ambient temperatures and does not mix with water but may mix with other oils and organic solvents. This general definition includes vegetable oils, volatile essential oils, petrochemical oils, and synthetic oils....

s, fat

Fat

Fats consist of a wide group of compounds that are generally soluble in organic solvents and generally insoluble in water. Chemically, fats are triglycerides, triesters of glycerol and any of several fatty acids. Fats may be either solid or liquid at room temperature, depending on their structure...

s, wax

Wax

thumb|right|[[Cetyl palmitate]], a typical wax ester.Wax refers to a class of chemical compounds that are plastic near ambient temperatures. Characteristically, they melt above 45 °C to give a low viscosity liquid. Waxes are insoluble in water but soluble in organic, nonpolar solvents...

es, grease

Grease (lubricant)

The term grease is used to describe semisolid lubricants. Although the word grease is also used to describe rendered fat of animals, in the context of lubrication, grease typically applies to a material consisting of a soap emulsified with mineral or vegetable oil...

s, various hydrocarbon

Hydrocarbon

In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. Hydrocarbons from which one hydrogen atom has been removed are functional groups, called hydrocarbyls....

 products, and acrylic

Acryl group

In organic chemistry, the acryloyl group is the functional group with structure H2C=CH–C–; it is the acyl group derived from acrylic acid. The preferred IUPAC name for the group is prop-2-enoyl, and it is also known as acrylyl or simply acryl...

 emulsion

Emulsion

An emulsion is a mixture of two or more liquids that are normally immiscible . Emulsions are part of a more general class of two-phase systems of matter called colloids. Although the terms colloid and emulsion are sometimes used interchangeably, emulsion is used when both the dispersed and the...

s.