A5533 Sigma-Aldrich

Alizarin Red S

certified by the Biological Stain Commission

Synonym: 3,4-Dihydroxy-9,10-dioxo-2-anthracenesulfonic acid sodium salt, Alizarin Carmine, Alizarin Red, water soluble, Alizarin sodium monosulfonate, Alizarin sulfonate sodium, Alizarinsulfonic acid sodium salt, Sodium alizarinsulfonate

  • CAS Number 130-22-3

  • Empirical Formula (Hill Notation) C14H7NaO7S

  • Molecular Weight 342.26

  •  Colour Index Number 58005

  •  Beilstein/REAXYS Number 4117090

  •  EC Number 204-981-8

  •  MDL number MFCD00013049

  •  PubChem Substance ID 24890988



Related Categories A, Analytical Reagents, Analytical/Chromatography, Cell Biology, Certified Stains & Dyes,
grade   certified by the Biological Stain Commission
form   powder
solubility   H2O: 1 mg/mL



• Alizarin Red S has been used for checking the calcium deposits in osteogenic culture.
• It has been used for the quantitative analyses of calcification in aortic explants.
• It has been used for mineral staining in osteoblast cultures.


25 g in glass bottle

Biochem/physiol Actions

Alizarin Red S is used for the staining of cartilage and bone. It reacts with calcium, thereby helping in the diagnosis of calcium deposits. It is also used to study carbohydrate–boronic acid interactions.


Certified for use in Dahl′s method for calcium

Safety & Documentation

Safety Information

Personal Protective Equipment 
NONH for all modes of transport
WGK Germany 


Certificate of Analysis


Certificate of Origin


Frequently Asked Questions

Which document(s) contains shelf-life or expiration date information for a given product?
If available for a given product, the recommended re-test date or the expiration date can be found on the Certificate of Analysis.
How do I get lot-specific information or a Certificate of Analysis?
The lot specific COA document can be found by entering the lot number above under the "Documents" section.
How do I find price and availability?
There are several ways to find pricing and availability for our products.Once you log onto our website, you will find the price and availability displayed on the product detail page.You can contact any of our Customer Sales and Service offices to receive a quote. USA customers: 1-800-325-3010 orview local office numbers.
What is the Department of Transportation shipping information for this product?
Transportation information can be found in Section 14 of the product's (M)SDS.To access the shipping information for this material, use the link on the product detail page for the product.
Product A5533, Alizarin Red S,is commonly used to stain calcium in tissue sections.Will other cations such as magnesium, manganese, barium and strontium also be detected?
No, typically only calcium is present in sufficient quantities to be demonstrated in tissue sections.
Product A5533, Alizarin Red S,has been prepared according to protocol. The solution has gelled or thickened. Is the solution still usable?
Yes. Although the solution has thickened or gelled, it is still suitable for use.
I see that Product A5533, Alizarin Red S, was tested according to the Dahl method at pH 7.0. Can the dye also be used in the McGee-Russell procedure at pH 4.2?
Yes. The dye can be used at a variety of pH values.
What are the pH transition ranges for Product A5533, Alizarin Red S?
Although the pH transition ranges are not determined on a lot to lot basis, the solution changes from yellow to red in the range of3.5-6.5, and from the orange to violet at pH 9.4-12. On a lot to lot basis there can be considerable difference in regards to color and pH ranges.
When using Product A5533, Alizarin Red S, will amorphous calcium deposits be detected in tissue sections?
Amorphous calcium phosphate deposits are very soluble below pH 8.5.In most instances the deposits are lost during either standard fixation or the during the standard staining procedure.
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