| Names | |
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| IUPAC name
Sodium 3,4-Dihydroxy-9,10-dioxo-9,10-dihydroanthracene-2-sulfonate | |
Other names
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| Identifiers | |
3D model (JSmol) |
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| ChEBI | |
| ChEMBL | |
| ChemSpider | |
| ECHA InfoCard | 100.004.530 |
| EC Number |
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PubChem CID |
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| UNII | |
CompTox Dashboard (EPA) |
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| Properties | |
| C14H7NaO7S | |
| Molar mass | 342.253 g/mol |
| Appearance | yellow-orange powder |
| Soluble in water and ethanol | |
| Hazards | |
| Safety data sheet (SDS) | |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Alizarin Red S (also known as C.I. Mordant Red 3, Alizarin Carmine, and C.I 58005.) is a water-soluble sodium salt of Alizarin sulfonic acid with a chemical formula of C
14H
7NaO
7S. Alizarin Red S was discovered by Graebe and Liebermann in 1871. In the field of histology alizarin Red S is used to stain calcium deposits in tissues, and in geology to stain and differentiate carbonate minerals.

Alizarin Red S is used in histology and histopathology to stain, or locate calcium deposits in tissues. In the presence of calcium, Alizarin Red S, binds to the calcium to form a Lake pigment that is orange to red in color. Whole specimens can be stained with Alizarin Red S to show the distribution of bone, especially in developing embryos. In living corals alizarin Red S has been used to mark daily growth layers.
In geology, Alizarin Red S is used on thin sections, and polished surfaces to help identify carbonate minerals which stain at different rates.