Orange G also called C.I. 16230, Acid Orange 10, or orange gelb is a synthetic

azo dye Azo dyes are organic compounds bearing the functional group R−N=N−R′, in which R and R′ are usually aryl and substituted aryl groups. They are a commercially important family of azo compounds, i.e. compounds containing the C-N ...

used in

histology Histology, also known as microscopic anatomy or microanatomy, is the branch of biology which studies the microscopic anatomy of biological tissues. Histology is the microscopic counterpart to gross anatomy, which looks at larger structures v ...

in many

staining Staining is a technique used to enhance contrast in samples, generally at the microscopic level. Stains and dyes are frequently used in histology (microscopic study of biological tissues), in cytology (microscopic study of cells), and in th ...

formulations. It usually comes as a disodium salt. It has the appearance of orange crystals or powder.

Staining

Orange G is used in the

Papanicolaou stain Papanicolaou stain (also Papanicolaou's stain and Pap stain) is a multichromatic (multicolored) cytological staining technique developed by George Papanicolaou in 1942. The Papanicolaou stain is one of the most widely used stains in cytology, ...

to stain

keratin Keratin () is one of a family of structural fibrous proteins also known as ''scleroproteins''. Alpha-keratin (α-keratin) is a type of keratin found in vertebrates. It is the key structural material making up Scale (anatomy), scales, hair, Nail ...

. It is also a major component of the Alexander test for pollen staining. It is often combined with other yellow dyes and used to stain

erythrocyte Red blood cells (RBCs), also referred to as red cells, red blood corpuscles (in humans or other animals not having nucleus in red blood cells), haematids, erythroid cells or erythrocytes (from Greek ''erythros'' for "red" and ''kytos'' for "hol ...

s in the

trichrome Trichrome staining is a histological staining method that uses two or more acid dyes in conjunction with a polyacid. Staining differentiates tissues by tinting them in contrasting colours. It increases the contrast of microscopic features in ...

methods.

Color marker

Orange G can be used as an

electrophoretic color marker An electrophoretic color marker is used to monitor the progress of agarose gel electrophoresis and polyacrylamide gel electrophoresis (PAGE) since DNA, RNA, and most proteins are colourless. They are also referred to as tracking dyes, and are freque ...

to monitor the process of

agarose gel electrophoresis Agarose gel electrophoresis is a method of gel electrophoresis used in biochemistry, molecular biology, genetics, and clinical chemistry to separate a mixed population of macromolecules such as DNA or proteins in a matrix of agarose, one of the ...

, running approximately at the size of a 50

Base pair A base pair (bp) is a fundamental unit of double-stranded nucleic acids consisting of two nucleobases bound to each other by hydrogen bonds. They form the building blocks of the DNA double helix and contribute to the folded structure of both D ...

(bp) DNA molecule, and polyacrylamide gel electrophoresis.

Bromophenol blue Bromophenol blue (3′,3″,5′,5″-tetrabromophenolsulfonphthalein, BPB), albutest is used as a pH indicator, an electrophoretic color marker, and a dye. It can be prepared by slowly adding excess bromine to a hot solution of phenolsulfonp ...

and

xylene cyanol Xylene cyanol can be used as an electrophoretic color marker, or tracking dye, to monitor the process of agarose gel electrophoresis and polyacrylamide gel electrophoresis. Bromophenol blue Bromophenol blue (3′,3″,5′,5″-tetrabromophen ...

can also be used for this purpose. (However, the apparent "size" of all these dyes varies according to the concentration of agarose in the gel and the buffer system used, so one should look up the appropriate reference before using the dyes to determine how far a gel has run.)

pH indicator

Despite its two ionizable groups, it shows only two colors in aqueous solution, brilliant orange in neutral and acidic pH or red in pH greater than 9.

References

{{Reflist, refs= {{cite book , editor1-last=Bancroft , editor1-first=John , editor2-last=Stevens , editor2-first=Alan , title=The Theory and Practice of Histological Techniques , date=1982 , publisher=Longman Group Limited , edition=2nd {{cite journal, author=Lillie RD, title=The hematoxylin shortage and the availability of synthetic substitutes. , journal=Am J Med Technol , year= 1974 , volume= 40 , issue= 11 , pages= 455–61 , pmid=4139897 , url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=4139897 Azo dyes Staining dyes 2-Naphthols Naphthalenesulfonates Organic sodium salts Acid dyes