Orang G

Orange G, also known by its Colour Index name Acid Orange 10, is an orange azo dye commonly used in histology and molecular biology. It plays a key role in the Masson-Goldner trichrome stain and can also serve as a tracking dye in agarose gel electrophoresis loading buffers. The dye exhibits pH-dependent color changes: it appears yellow at pH 11.5 and turns pink at pH 14.0.
🏭⚗️ Synthesis
Orange G is synthesized through an azo coupling reaction between diazotized aniline and 2-naphthol-6,8-disulfonic acid, also known as G-acid—one of the so-called “letter acids.”
🧪 Applications
• Histology: Used as a collagen stain in connective tissue staining.
• Kornhauser’s Quadruple Stain: Applied alongside Orcein, Alizarin Blue 2B, and Fast Green FCF to visualize key tissue structures.
• Masson Trichrome Stain: Combined with acid fuchsin and light green to stain cellular components, red blood cells, and muscle fibers.
• Electrophoresis: Serves as a marker dye in agarose gel loading buffers.