Understanding CAS Numbers
Before identifying the specific CAS number for creatine, it is helpful to understand what these numbers represent. A CAS Registry Number is a unique numerical identifier for chemical substances. Every chemical that has been documented in the Chemical Abstracts Service (CAS) registry is assigned one of these numbers. They are universally used in science, industry, and by regulatory bodies to provide an unambiguous way to identify a chemical substance, regardless of its name, which can vary by region or language.
The Purpose of CAS Registry Numbers
CAS numbers serve several important functions in the chemical world, including:
- Universal Identification: A specific CAS number corresponds to only one substance, preventing confusion that might arise from common names, chemical formulas, or different scientific nomenclature.
- Regulatory Compliance: They are essential for tracking and regulating chemical substances by government agencies worldwide.
- Research and Safety: Researchers and laboratories use them to access information about a compound's properties, toxicity, and safety data.
What is the CAS number of creatine?
Creatine actually has more than one CAS number, depending on its specific chemical form. The primary distinction is between anhydrous creatine and creatine monohydrate, the latter being the most common form found in dietary supplements.
Anhydrous Creatine (CAS 57-00-1)
The CAS number for anhydrous creatine is 57-00-1. Anhydrous creatine is creatine in its pure form, without any water molecules attached to its structure. While not as common as the monohydrate form in supplements, this is the identifier for the creatine molecule itself.
Creatine Monohydrate (CAS 6020-87-7)
The CAS number for creatine monohydrate is 6020-87-7. This is the most widely studied and commercially available form of creatine, and its chemical structure includes one molecule of water ($H_2O$) for every molecule of creatine. For supplement users, this is the most relevant CAS number.
Other Identifiers and Synonyms
Beyond its CAS numbers, creatine is also known by other names and identifiers, including:
- IUPAC Name: 2-[carbamimidoyl(methyl)amino]acetic acid
- PubChem CID: 586
- DrugBank ID: DB00148
- Synonyms: N-amidinosarcosine, N-carbamimidoyl-N-methylglycine, Methylguanidoacetic acid.
Creatine Anhydrous vs. Monohydrate: A Comparison
To highlight the key differences between the two main forms, here is a comparison table:
| Property | Anhydrous Creatine | Creatine Monohydrate |
|---|---|---|
| CAS Number | 57-00-1 | 6020-87-7 |
| Chemical Formula | C4H9N3O2 | C4H9N3O2 · H2O |
| Molecular Weight | 131.135 g/mol | 149.15 g/mol |
| Presence of Water | None | Contains one water molecule per molecule of creatine |
| Commonality in Supplements | Less common | Most common and widely studied form |
| Purity | Often a higher concentration of pure creatine by weight due to the absence of water. | Typically sold with high purity, often exceeding 99%. |
| Stability | More stable in solution at lower pH levels compared to monohydrate. | Less stable in solution and should be consumed soon after mixing, or refrigerated. |
The Manufacturing and Purity of Creatine
Creatine is typically synthesized industrially using a process that involves cyanamide and sarcosine. The purity of the final product, especially creatine monohydrate, is crucial to ensure safety and effectiveness. Low-purity creatine can contain harmful byproducts such as dicyandiamide. Many reputable manufacturers, such as those producing Creapure®, ensure 99.9% purity through rigorous quality control. Consumers should be mindful of the source and purity of their supplements.
Regulatory Status and Safety of Creatine
Creatine's regulatory status varies globally, but it is generally recognized as safe (GRAS) for use in dietary supplements. In the United States, creatine monohydrate is a "grandfathered" ingredient under the Dietary Supplement Health and Education Act (DSHEA). Organizations like the FDA and NCAA allow its use, differentiating it clearly from anabolic steroids. While creatine is well-researched and safe for most healthy individuals, it is not recommended for people with pre-existing kidney or liver conditions. Common side effects can include temporary water retention and slight gastrointestinal discomfort.
Conclusion
For those seeking to understand the chemical identity of this popular supplement, knowing what the CAS number of creatine is clarifies its precise form. The key distinction lies between anhydrous creatine (CAS: 57-00-1) and creatine monohydrate (CAS: 6020-87-7). The CAS registry provides a standardized, universal method for identifying these compounds, ensuring clarity in scientific research, manufacturing, and regulation. It is a fundamental tool for documenting the chemical substances we interact with daily.
Learn more about creatine and its chemical properties by visiting the U.S. National Library of Medicine's PubChem database.
