Orange G

  Orange G, Acid Orange 10, or C.I. 16230, is a synthetic azo dye used in histology in many staining formulations. It usually comes as a disodium salt. It has the appearance of orange crystals or powder.

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The main use of Orange G is in the OG6 Papanicolaou stain, to stain keratin, however 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 erythrocytes in the trichrome methods.

Orange G can be used as a color marker to monitor the process of agarose gel electrophoresis, running approximately at the size of a 50 Base pair (bp) DNA molecule, and polyacrylamide gel electrophoresis. Bromophenol blue and xylene cyanol can also be used for this purpose.

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. When exposed to UVs show a light blue fluorescence.

Its CAS number is [1936-15-8] and its SMILES structure is Oc1ccc2cc(OS([O-])=O)cc(OS([O-])=O)c2c1N=Nc3ccccc3. Its risk and safety phrases are R36/37/38 S26 S36.