Neutral red is a high-grade reagent supplied by Micromaster. Few other chemical names used to denote this reagent include, toluylene red, basic red 5 and 3-Amino-7-dimethylamino-2-methylphenazine hydrochloride. It is generally manufactured as a chloride salt. It is available in the form of a red brown solid which is odourless. It is insoluble in water. It is stable if stored according to the recommended conditions. It is incompatible with strong oxidising agents. Avoid dust formation and excess heat conditions near this product.

• CAS No. 553-24-2
• Quantity provided: 100 g/pack
• Molecular formula: C₁₅H₁₇ClN₄
• Molecular weight: 288.779 g/mol

Neutral red is a eurhodin dye used for staining in histology as it stains lysosomes red. It is used as a general stain in histology, as a counterstain in combination with other dyes and for many staining methods. In microbiology, it is used in the MacConkey agar to differentiate bacteria for lactose fermentation. The neutral red dye uptake is a cytotoxicity assay, which provides quantitative estimation of number of viable cells in a culture by measuring the ability of test compound to inhibit uptake of neutral red dye. Neutral red is added to some growth media for bacterial and cell cultures. It usually is available as a chloride salt. Neutral red also can be used as a pH indicator as it changes from red to yellow between pH 6.8 and 8.0. It is used to stain cell cultures for plate titration of viruses. Neutral red is added to some growth media for bacterial and cell cultures.