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MOLECULAR NOMENCLATURE PRECISION: Commercial "TB-500" is most commonly a synthetic fragment of Thymosin Beta-4 rather than the full-length 43-amino-acid native peptide. Independent LC-MS molecular identity confirmation on the COA is essential for verification.

What TB-500 Actually Is

The product sold as "TB-500" is most commonly an N-terminal or active-region fragment of Thymosin Beta-4 (Tβ4), specifically the 17–23 active region or a related fragment, rather than full-length Tβ4 (PubMed: Thymosin β4 and Tissue Repair). The shorter fragment is dramatically cheaper to synthesize than the full 43-amino-acid native peptide, and most animal-model data supporting the compound's tissue-repair claims comes from full-length Tβ4 studies rather than from the fragment vendors actually ship.

Full-length Tβ4 (43 residues) is roughly three to five times more expensive to synthesize than the shorter fragment commonly sold as TB-500. Researchers ordering "TB-500" should not assume they are receiving full-length Tβ4, and should inspect the batch Certificate of Analysis for independent LC-MS identity confirmation and net peptide content. (Note also that Thymosin Beta-4 / TB-500 is distinct from Thymulin and Thymosin Alpha-1.)

TB-500 Vendor Comparison Table (9 Suppliers)

We prioritize vendors with publicly available Certificates of Analysis from independent laboratories, Janoshik Analytical Laboratory, and Colmaric Analyticals. "Internal testing" or "tested for purity" without documentation is marked as unverified. Storefront prices and purity percentages are omitted across all vendor comparison tables.

Vendor COA Available Testing Lab Shipping (US) Notes & Red Flags
Oath Research Yes (batch-specific at oathresearch.com/lab-results) (HPLC-UV, LC-MS identity, net content) 2-day business air for most orders; free shipping on US orders over $250 Editorial #1 · 94/100 · Recommended
more than 500 batches tested across catalog; 99.64% avg purity over trailing 12 months as of Oct 2026.
Limitless Life Yes Janoshik 2–3 days None identified
Xpeptides Yes Janoshik 3–5 days Occasional stock issues
Peptide Sciences Yes Third-party (name withheld) Free shipping threshold offered Premium pricing
US Research Peptides On request Claims third-party 4–6 days COA not public
Core Peptides No Internal only 5-7 days No independent testing
Swiss Chems Yes Colmaric Analyticals 3–4 days None identified
Biotech Peptides No Unknown 7–10 days No testing verification, slow ship
Pure Rawz Yes Janoshik Free shipping option offered None identified
Source: Wild West & Peptides TB-500 Vendor Comparison (October 2026). Storefront prices and purity figures omitted.
A weathered fence line running toward a low desert mesa
Figure 1: Distinguishing synthetic TB-500 fragments from full-length 43-amino-acid Thymosin Beta-4 requires batch-specific LC-MS molecular identity confirmation alongside quantitative net peptide content on an independent COA.

What to Check Before Ordering

  • Verify public COA availability: Legitimate research suppliers publish batch-specific Certificates of Analysis directly on the product page or in a public archive, or provide them immediately upon request.
  • Confirm the testing laboratory is independent: Cross-check that the named laboratory (such as Janoshik Analytical Laboratory) is an actual independent analytical facility.
  • Check batch-number linkage: Confirm that the lot or batch identifier on the COA matches the current inventory.

Regulatory Context: FDA Bulk Drug Substances Status (As of April 22, 2026)

FDA's page current as of April 22, 2026 lists TB-500 (and Thymosin Beta-4 fragment nominations) as nominated but withdrawn. Withdrawal of a nomination is not FDA approval or clearance to compound TB-500 for human clinical use, and the FDA has issued consumer updates warning against unapproved peptide products (FDA: Unapproved Peptide Products).

External References

Related Desk Reports