AssayIndex
Tissue-repair and immunomodulatory peptides

TB-500

thymosin β4 fragment (17-23) · Ac-LKKTETQ · C39H69N9O14 · monoisotopic 887.4964 Da. The index holds 356 assay reports on this compound across 67 batches from 17 suppliers.

356 reports67 batchesmedian 99.47 %index spec 98.5 %
Section 1

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.

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
Section 2

Representative chromatogram

Drawn from this page's own medians. Not a scan, not an illustration, and not any single report.

0341768351025213670 TB-5007.86 min · 99.47 % 7.34 same trace · ×200 vertical expansion, baseline-corrected · main peak off-scale reporting threshold 0.05 % area 05101520253035 Retention time (min) Response (mAU)
Figure 1. A representative TB-500 trace on the index reference method RG-2, constructed from this page's own numbers: the main peak carries the index median purity of 99.47 % area at the nominal retention time of 7.86 min, and each impurity peak carries the median area the index has observed for that named species at its characteristic retention offset. It is not a scan of any single report — every individual record's own chromatogram is on its own page. The lower panel is the same trace at a stated vertical expansion, baseline-corrected, so the impurities are visible; the main peak runs off-scale there by design. Baseline noise is seeded from the compound slug.
Section 3

What the index has observed

Arithmetic over the 356 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.

Median purity 99.47% n=356
Interquartile range 0.82pp n=356
Minimum 97.40% n=356
Maximum 99.93% n=356
Pass rate vs spec 89.0% n=356
Median recovery vs claim 98.9% n=213
Median water 4.45% n=356
Median |mass error| 2.4ppm n=310
030609092.093.094.095.096.097.098.099.0100.092.00–92.25 %: n=092.25–92.50 %: n=092.50–92.75 %: n=092.75–93.00 %: n=093.00–93.25 %: n=093.25–93.50 %: n=093.50–93.75 %: n=093.75–94.00 %: n=094.00–94.25 %: n=094.25–94.50 %: n=094.50–94.75 %: n=094.75–95.00 %: n=095.00–95.25 %: n=095.25–95.50 %: n=095.50–95.75 %: n=095.75–96.00 %: n=096.00–96.25 %: n=096.25–96.50 %: n=096.50–96.75 %: n=096.75–97.00 %: n=097.00–97.25 %: n=097.25–97.50 %: n=297.50–97.75 %: n=297.75–98.00 %: n=1198.00–98.25 %: n=998.25–98.50 %: n=1598.50–98.75 %: n=1698.75–99.00 %: n=3699.00–99.25 %: n=3199.25–99.50 %: n=5899.50–99.75 %: n=7199.75–100.00 %: n=105median 99.47 Purity (% area) Reports
Figure 2. Purity distribution across all 356 TB-500 records. Dashed line is this compound's median (99.47 %); the solid vertical is the index acceptance specification for the tissue-repair and immunomodulatory peptides class (98.5 %). Domain is fixed at 92–100 % on every purity histogram on this site so that compounds can be compared by eye — a wide distribution here is a hard compound, a narrow one is an easy one, and neither is a statement about the suppliers.
Section 4

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.

97.297.798.298.799.299.6100.1QSCQSC: Q1 99.55, median 99.80, Q3 99.93, n=56outlier 98.52outlier 98.54outlier 98.90n=56QYBQYB: Q1 99.37, median 99.51, Q3 99.70, n=34outlier 98.59n=34JEEPJEEP: Q1 99.52, median 99.72, Q3 99.93, n=26outlier 98.85outlier 98.86n=26FGPFGP: Q1 99.38, median 99.68, Q3 99.93, n=26n=26WXTWXT: Q1 97.81, median 98.03, Q3 98.30, n=26outlier 99.07outlier 99.17n=26HomopeptideHomopeptide: Q1 99.13, median 99.38, Q3 99.69, n=26n=26CPCCPC: Q1 98.38, median 98.96, Q3 99.37, n=25n=25TFCTFC: Q1 98.99, median 99.69, Q3 99.93, n=25n=25ERPERP: Q1 98.95, median 99.23, Q3 99.55, n=22n=22GGPepsGGPeps: Q1 99.12, median 99.52, Q3 99.68, n=19n=19WWBWWB: Q1 99.58, median 99.79, Q3 99.93, n=17n=17HJHJ: Q1 99.30, median 99.56, Q3 99.77, n=14n=14KPKP: Q1 98.77, median 99.19, Q3 99.49, n=14n=14SSASSA: Q1 98.38, median 98.59, Q3 98.91, n=12n=12MKMMKM: Q1 99.39, median 99.59, Q3 99.82, n=11n=11SGNSGN: Q1 98.94, median 99.02, Q3 99.09, n=2n=2 Purity (% area)
Figure 3. TB-500 purity by supplier, ordered by coverage. The vertical line is the index acceptance specification. Boxes that overlap are suppliers this dataset cannot separate, and most of them overlap.

Full per-supplier table with n= caveats →

Section 5

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 speciesΔRT (min, RG-2)Δ mass (Da)Seen inMedian % areaMax % area
C-terminal amide (−1 Da)+0.18-0.98491%0.101.54
des-acetyl TB-500 (−42 Da)-0.52-42.01188%0.111.11
des-Gln truncate (−128 Da)-0.24-128.05987%0.091.77
[D-Thr]-diastereomer-0.11mass-identical85%0.101.51

Degradation pathways

  • acetyl loss under acidic hydrolysis
  • no oxidative liability

Full impurity profile, with what each named species implies about the synthesis →

Section 7

Quarterly coverage

QuarterReportsMedian purityRange
2024-Q1799.4698.86–99.82
2024-Q22099.6199.05–99.93
2024-Q31199.2998.49–99.70
2024-Q42098.8698.22–99.93
2025-Q15899.6997.86–99.93
2025-Q23599.8098.46–99.93
2025-Q34099.0997.52–99.93
2025-Q45699.0397.40–99.93
2026-Q14999.6898.90–99.93
2026-Q24299.4797.95–99.93
2026-Q31899.7299.41–99.93

Quarter-by-quarter detail →

Section 8

Most recent records

The 25 most recent TB-500 records of 356.
ReportSupplierLotLabQuarterPurity %Water %Recovery %ProvenanceFlagsResult
AX-2026-041847JEEPJEEP-2602-V3434Nordanalyt2026-Q399.723.85—Supplier-supplied1MARGINAL
AX-2026-042574ERPERP-2605-S8022VendorInvestigate2026-Q399.542.9196.4Buyer-sourced1MARGINAL
AX-2026-042577ERPERP-2605-S8022Janoshik2026-Q399.513.45—Supplier-supplied1MARGINAL
AX-2026-041845JEEPJEEP-2602-V3434Janoshik2026-Q399.724.04102.2Supplier-supplied1MARGINAL
AX-2026-041921JEEPJEEP-2605-M4874Janoshik2026-Q399.901.76—Supplier-supplied2MARGINAL
AX-2026-041922JEEPJEEP-2605-M4874Janoshik2026-Q399.412.6095.7Laboratory-retained2MARGINAL
AX-2026-041928JEEPJEEP-2605-M4874Janoshik2026-Q399.881.8492.8Laboratory-retained2MARGINAL
AX-2026-041849JEEPJEEP-2602-V3434VendorInvestigate2026-Q399.733.6088.6Buyer-sourced2MARGINAL
AX-2026-041926JEEPJEEP-2605-M4874Medutest2026-Q399.932.15106.8Supplier-supplied1MARGINAL
AX-2026-041925JEEPJEEP-2605-M4874PeptideMeter2026-Q399.932.15—Supplier-supplied2MARGINAL
AX-2026-041850JEEPJEEP-2602-V3434Medutest2026-Q399.933.4499.1Supplier-supplied2FAIL
AX-2026-042575ERPERP-2605-S8022Janoshik2026-Q399.933.3695.5Supplier-supplied0PASS
AX-2026-042576ERPERP-2605-S8022PeptideMeter2026-Q399.552.9894.5Supplier-supplied1MARGINAL
AX-2026-041924JEEPJEEP-2605-M4874PeptideMeter2026-Q399.451.54—Laboratory-retained2MARGINAL
AX-2026-041848JEEPJEEP-2602-V3434Janoshik2026-Q399.503.15—Supplier-supplied1MARGINAL
AX-2026-041923JEEPJEEP-2605-M4874PeptideMeter2026-Q399.591.63104.1Supplier-supplied2MARGINAL
AX-2026-041846JEEPJEEP-2602-V3434Janoshik2026-Q399.933.30—Supplier-supplied1MARGINAL
AX-2026-041927JEEPJEEP-2605-M4874Nordanalyt2026-Q399.761.75105.3Supplier-supplied2MARGINAL
AX-2026-042822GGPepsGGPE-2605-J2051PeptideMeter2026-Q299.344.28—Supplier-supplied1MARGINAL
AX-2026-042350HJHJ-2511-L4170Medutest2026-Q299.712.9196.7Supplier-supplied1MARGINAL
AX-2026-042352HJHJ-2511-L4170Janoshik2026-Q299.932.64100.6Supplier-supplied1MARGINAL
AX-2026-042758GGPepsGGPE-2601-B9932Janoshik2026-Q299.524.9294.9Supplier-supplied1MARGINAL
AX-2026-042817GGPepsGGPE-2605-J2051Janoshik2026-Q299.914.2789.4Supplier-supplied2MARGINAL
AX-2026-042824GGPepsGGPE-2605-J2051PeptideMeter2026-Q299.614.65—Supplier-supplied1MARGINAL
AX-2026-043341CPCCPC-2605-B2433Janoshik2026-Q298.385.70—Laboratory-retained2FAIL