Thymalin is a thymus-derived polypeptide preparation, not a single defined molecule. On the analytical side, that distinction is the whole story. NLM catalogues it as the supplementary concept thymalin, registry number 79621-14-0. The same CAS number appears in the ChemIDplus substance record and in EPA DSSTox. What none of those records carries is a molecular formula.
This note is a research-context description only. It is not a claim of benefit, outcome, or suitability for any use in a person or animal. Thymalin from Elev8 Labs ships as a laboratory reference standard.
There is no single mass, and that is the point
A PubChem name search for "thymalin" does not return a Thymalin record. It resolves to CID 3085284, titled Nonathymulin — C₃₃H₅₄N₁₂O₁₅, 858.9 g/mol, CAS 63958-90-7. That is a defined nonapeptide, a different substance with a different CAS number. "Thymalin" sits in its synonym list as a cross-reference, which is how the wrong 858.9 g/mol ends up copied onto vendor pages.
Do not inherit that number. Thymalin has no PubChem compound record of its own, no ChEMBL entry, and no molecular formula in any registry we checked. A related NLM record, thymarin (67775-02-4), states the position plainly: the registry number refers to a compound with unknown molecular formula.
That changes what a certificate can honestly say. You cannot validate a mixture against one expected mass. Characterization is by profile, not by a single number.
What the published record contains
PubMed indexes 293 records for the term as of August 2026, under the same supplementary concept. Published work spans:
- Peptide-complex chemistry — separation and profiling of thymus-derived polypeptide fractions
- In-vitro cell-line work — including monocyte/macrophage line studies (PMID 35408963), which describes the material as the "Thymalin® peptide complex"
- Comparative bench studies against defined short peptides of known sequence
- Analytical method work for heterogeneous, biologically sourced preparations
The literature exists and is indexed. Nothing in it is reproduced here as a result.
Regulatory status, stated plainly
We checked this directly. The FDA drugsfda endpoint at api.fda.gov returns no match for Thymalin on brand, generic, or substance name. DailyMed returns zero labeled products under that name. No approved US drug carries it, so there is no brand collision.
Thymalin is not an approved drug in the United States, and we do not supply it as one. Any registration it holds elsewhere is outside our scope and is not an endorsement.
Characterizing a fraction
A single-peak purity percentage is the wrong specification for a mixture. What a Thymalin reference lot can be held to instead:
- Chromatographic profile by RP-HPLC, compared lot-to-lot against a retained reference profile
- Total peptide content, reported with the method used to determine it
- Source and lot traceability — starting material tracked from raw lot to vial
- Residual moisture and appearance for the lyophilized powder
- Independent analytical COA, not self-certified, with the lot number matching vial and shipment record
The frameworks behind those lines are public. Chromatographic system suitability sits in USP General Chapter ⟨621⟩ Chromatography, mass-based identity in USP ⟨736⟩ Mass Spectrometry, and method validation in ICH Q2(R2). For heterogeneous biologically sourced material specifically, ICH Q6B, Specifications: Test Procedures and Acceptance Criteria for Biotechnological/Biological Products is the guideline that addresses profile-based specification. "Independent" is verifiable too — ISO/IEC 17025 accreditation is listed by NIST's NVLAP and by the ILAC Mutual Recognition Arrangement.
A supplier who quotes 858.9 g/mol for Thymalin has copied a cross-reference without reading it. Ask which record the number came from.
What is out of scope
Questions about human use, quantities, schedules, combinations, or any personal-use scenario are out of scope for Elev8 Labs. We do not provide that information and we do not supply material configured for it. Our business ends at the analytical bench.
Analytical, method-development, and lot-availability questions are welcome at support@elev8labsrx.com.
Elev8 Labs products are reference standards for laboratory research only. Not for human consumption.