TB-500 (Thymosin Beta-4 Fragment) Testing & Verification
Independent, third-party verification of mail-in TB-500 samples by reversed-phase HPLC. We confirm what your vial actually contains — identity, chromatographic purity, and net peptide content — against a certified reference standard.
What TB-500 is
TB-500 is a synthetic peptide most often sold as the acetylated actin-binding fragment of thymosin beta-4 (Tβ4): an N-terminally acetylated seven-residue (heptapeptide) sequence, Ac-LKKTETQ, corresponding to residues 17–23 of the parent protein, with a reported average molecular weight near 889 g/mol. Confusingly, some products labeled "TB-500" instead contain full-length thymosin beta-4, a roughly 43-residue protein of about 4,900 g/mol — a chemically distinct molecule that only shares part of its sequence with the fragment. It is a research chemical and is not an FDA-approved drug. Because it typically ships as a lyophilized powder that the buyer reconstitutes, none of its identity, purity, or content can be confirmed by visual inspection.
Why get your TB-500 independently tested
- Fragment vs. full protein: "TB-500" is used in the market for two different molecules — the ~889 g/mol acetylated heptapeptide fragment (Ac-LKKTETQ) and full-length 43-residue thymosin beta-4 (~4,900 g/mol). Retention-time and UV-spectral comparison against a certified reference standard confirms which one you actually received.
- Acetylation and sequence integrity: the N-terminal acetyl group and the exact residue order are defining structural features. Identity testing checks that your peptide matches the certified reference rather than a truncated, deletion, or otherwise mislabeled sequence.
- Net-peptide content vs. label: vials sold by mass (e.g., 5 mg or 10 mg) can contain a blend of peptide, counter-ions, residual water, and salts. A net-peptide assay reports the actual milligrams of peptide per vial, exposing underfilling or an overstated label claim.
- Chromatographic purity: solid-phase peptide synthesis leaves process-related impurities and byproducts behind. Area-percent purity by HPLC quantifies how much of the material is the target peptide versus everything else co-eluting in the vial.
What we measure on TB-500
Every TB-500 sample is analyzed by RP-HPLC with UV/diode-array detection at 214 nm against a certified reference standard. We report exactly three results per certificate: identity (retention-time plus UV-spectral match to the reference), chromatographic purity expressed as area percent, and net-peptide assay expressed as milligrams of peptide per vial. We do not perform mass spectrometry, sterility, or endotoxin testing.
Every result is issued as a certificate of analysis you — or anyone you forward it to — can verify cryptographically. Reporting identity, purity, and milligram content is the point: a vial can be pure and still underfilled, so we report all three. More on purity vs. net-peptide content and how to read a peptide COA.
Our scope — stated plainly
Testing is RP-HPLC-UV against a certified reference standard and establishes identity, chromatographic purity, and net peptide content — not sterility, safety, or fitness for any use. Because TB-500 is a less-common peptide sold in more than one form, a certified reference standard matching your product may need to be sourced before analysis, which can affect turnaround.
KMD is an independent RP-HPLC-UV lab. We do not run LC-MS / mass-spec, sterility, endotoxin, or heavy-metal testing. If your job needs a capability we don't have, we'll say so.
TB-500 testing — FAQ
Can you tell whether my vial is the heptapeptide fragment or full-length thymosin beta-4?
RP-HPLC-UV compares your sample's retention time and UV spectrum to a certified reference standard, so results reflect whichever standard we run against. Tell us which molecule you believe you purchased and we will match it to the appropriate reference; the two forms are chemically distinct and elute differently.
Do you confirm the exact sequence or the acetyl group by mass spec?
No. We use RP-HPLC-UV, which establishes identity by retention-time and UV-spectral match to a reference standard, not by molecular mass. We do not run LC-MS or any mass-spectrometric methods.
What exactly do I get on the certificate?
Three results: identity (match to a certified reference standard), chromatographic purity as area percent, and net-peptide assay in milligrams per vial. Mail in your sample and we analyze it as received.
Other peptides we test
Retatrutide · Cagrilintide · Tesamorelin · BPC-157 · see the full panel.