TB-500
thymosin β4 fragment (17-23) · Ac-LKKTETQ · C39H69N9O14 · monoisotopic 887.4964 Da. The index holds 268 assay reports on this compound across 57 batches from 23 suppliers.
Analytical fingerprint
Hand-authored chemistry. These properties describe the substance and do not change when a record is added.
TB-500 is a seven-residue acetylated fragment, not thymosin β4, and the distinction accounts for the largest single class of labelling error in the index: full-length Tβ4 is 4963 Da against TB-500's 887 Da, so mass identification is trivial, yet product labels use the names interchangeably. Where a submission labelled TB-500 masses as full-length Tβ4 the index records the correct compound and files a labelling note against the batch, not a purity failure. Assay itself is simple; purity is uniformly high and does not discriminate between suppliers.
- Compound class
- Tissue-repair and immunomodulatory peptides
- Molecular formula
- C39H69N9O14
- Monoisotopic mass
- 887.4964Da
- Average mass
- 888.01Da
- Residues
- 7
- Nominal retention (RG-2, 30 min)
- 7.86min
- Retention window
- 0.25min
- Counter-ion as usually shipped
- acetate
- Typical label claims
- 2 mg · 5 mg · 10 mg
- Analytical difficulty (index scale)
- 0.85 — straightforward
- Purity is a defined quantity
- YES
Representative chromatogram
Drawn from this page's own medians. Not a scan, not an illustration, and not any single report.
What the index has observed
Arithmetic over the 268 records the index holds. Aggregates on this page are computed over the records the index holds, which are not a random sample of the material on the market. Lots that get tested are lots someone chose to test. Read every figure here as a description of this dataset rather than as an estimate of a population.
By supplier
Suppliers with fewer than two purity records on this compound are omitted from the figure rather than drawn as a line. The full table, including the thin cells, is on the by-supplier page.
Characteristic impurities and degradants
The left three columns are authored chemistry — what this molecule characteristically carries and where it elutes. The right three are what the index has actually reported.
| Named species | ΔRT (min, RG-2) | Δ mass (Da) | Seen in | Median % area | Max % area |
|---|---|---|---|---|---|
| des-acetyl TB-500 (−42 Da) | -0.52 | -42.011 | 91% | 0.11 | 0.79 |
| des-Gln truncate (−128 Da) | -0.24 | -128.059 | 90% | 0.09 | 1.48 |
| C-terminal amide (−1 Da) | +0.18 | -0.984 | 86% | 0.08 | 1.35 |
| [D-Thr]-diastereomer | -0.11 | mass-identical | 85% | 0.08 | 1.16 |
Degradation pathways
- acetyl loss under acidic hydrolysis
- no oxidative liability
Full impurity profile, with what each named species implies about the synthesis →
Quarterly coverage
| Quarter | Reports | Median purity | Range |
|---|---|---|---|
| 2024-Q1 | 21 | 99.51 | 99.21–99.93 |
| 2024-Q2 | 12 | 99.30 | 98.44–99.79 |
| 2024-Q3 | 2 | n<3 | 99.90–99.93 |
| 2024-Q4 | 26 | 98.87 | 98.11–99.54 |
| 2025-Q1 | 23 | 99.50 | 98.45–99.93 |
| 2025-Q2 | 21 | 99.73 | 98.99–99.93 |
| 2025-Q3 | 20 | 99.31 | 98.47–99.74 |
| 2025-Q4 | 39 | 99.43 | 97.79–99.93 |
| 2026-Q1 | 51 | 99.67 | 99.09–99.93 |
| 2026-Q2 | 35 | 99.59 | 98.15–99.93 |
| 2026-Q3 | 18 | 99.91 | 99.53–99.93 |