AssayIndex
Tissue-repair and immunomodulatory peptides

Thymosin α1

Tα1 · thymalfasin · Zadaxin · C129H215N33O55 · monoisotopic 3106.5493 Da. The index holds 24 assay reports on this compound across 7 batches from 6 suppliers.

24 reports7 batchesmedian 99.11 %index spec 97.5 %
Section 1

Analytical fingerprint

Hand-authored chemistry. These properties describe the substance and do not change when a record is added.

Thymosin α1 is N-terminally acetylated and the des-acetyl species is the dominant real-lot impurity, 0.68 min early. It is the only compound in the index with an approved reference product available in several markets, which makes it useful for method cross-checks: labs that can reproduce the reference standard's impurity profile on RG-2 are demonstrating genuine method capability. Two of the six index labs publish that comparison; the other four do not, and their thymosin α1 figures carry a method-transparency note.

Molecular formula
C129H215N33O55
Monoisotopic mass
3106.5493Da
Average mass
3108.29Da
Residues
28
Nominal retention (RG-2, 30 min)
12.72min
Retention window
0.30min
Counter-ion as usually shipped
acetate
Typical label claims
1.6 mg · 5 mg · 10 mg
Analytical difficulty (index scale)
1.10 — 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.

02104420863138417 Thymosin α112.72 min · 99.11 % 13.14 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 Thymosin α1 trace on the index reference method RG-2, constructed from this page's own numbers: the main peak carries the index median purity of 99.11 % area at the nominal retention time of 12.72 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 24 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 99.11% n=24
Interquartile range 1.00pp n=24
Minimum 97.83% n=24
Maximum 99.71% n=24
Pass rate vs spec 100.0% n=24
Median recovery vs claim 99.0% n=14
Median water 3.27% n=24
Median |mass error| 3.2ppm n=21
024692.093.094.095.096.097.098.099.0100.092.00–92.25 %: 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=097.50–97.75 %: n=097.75–98.00 %: n=398.00–98.25 %: n=298.25–98.50 %: n=398.50–98.75 %: n=098.75–99.00 %: n=399.00–99.25 %: n=499.25–99.50 %: n=799.50–99.75 %: n=299.75–100.00 %: n=0median 99.11 Purity (% area) Reports
Figure 2. Purity distribution across all 24 Thymosin α1 records. Dashed line is this compound's median (99.11 %); the solid vertical is the index acceptance specification for the tissue-repair and immunomodulatory peptides class (97.5 %). 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.

97.798.098.498.899.199.599.9SWBSWB: Q1 99.24, median 99.30, Q3 99.36, n=9outlier 98.96outlier 99.71n=9CPCCPC: Q1 97.90, median 97.94, Q3 98.14, n=5n=5SSASSA: Q1 98.28, median 98.63, Q3 99.01, n=4n=4FGPFGP: Q1 98.65, median 98.89, Q3 99.22, n=3n=3SGNSGN: Q1 99.18, median 99.23, Q3 99.28, n=2n=2 Purity (% area)
Figure 3. Thymosin α1 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
des-acetyl Tα1 (−42 Da)-0.68-42.011100%0.201.24
deamidated Asn (+1 Da)-0.34+0.984100%0.191.09
truncated (1-24)-1.24-487.229100%0.150.44
aspartimide (−18 Da)+0.42-18.011100%0.251.19

Degradation pathways

  • N-terminal acetyl loss
  • Asn deamidation
  • aspartimide at Asp-Gly

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

Section 6

Clinical context

Included because it is routinely misapplied. Trial data describes a licensed medicinal product manufactured under a marketing authorisation, and it does not transfer to research-grade material of unknown provenance.

Thymalfasin is approved in a number of countries for chronic hepatitis B and as an immune adjuvant; it is not approved in the United States.

Section 7

Quarterly coverage

QuarterReportsMedian purityRange
2024-Q10n<3—
2024-Q20n<3—
2024-Q3498.6398.23–99.13
2024-Q40n<3—
2025-Q10n<3—
2025-Q20n<3—
2025-Q31599.2497.83–99.71
2025-Q40n<3—
2026-Q1499.1698.41–99.55
2026-Q21n<3—
2026-Q30n<3—

Quarter-by-quarter detail →

Section 8

Most recent records

The 25 most recent Thymosin α1 records of 24.
ReportSupplierLotLabQuarterPurity %Water %Recovery %ProvenanceFlagsResult
AX-2026-043213SGNSGN-2512-Y1213Janoshik2026-Q299.137.01—Buyer-sourced1MARGINAL
AX-2026-041468QYBQYB-2511-V6148Kestrel2026-Q199.442.86101.7Supplier-supplied2MARGINAL
AX-2026-041831FGPFGP-2511-H2692PeptideMeter2026-Q199.555.0995.2Supplier-supplied0PASS
AX-2026-041830FGPFGP-2511-H2692PeptideMeter2026-Q198.895.0499.1Supplier-supplied0PASS
AX-2026-041832FGPFGP-2511-H2692Medutest2026-Q198.414.46—Supplier-supplied0PASS
AX-2025-019905SWBSWB-2503-S5672Janoshik2025-Q398.963.36—Supplier-supplied0PASS
AX-2025-020891CPCCPC-2504-M1855Janoshik2025-Q398.145.19104.6Supplier-supplied0PASS
AX-2025-019906SWBSWB-2503-S5672Janoshik2025-Q399.713.18—Supplier-supplied0PASS
AX-2025-019909SWBSWB-2503-S5672Janoshik2025-Q399.243.04102.0Supplier-supplied0PASS
AX-2025-020889CPCCPC-2504-M1855PeptideMeter2025-Q397.904.86—Supplier-supplied0PASS
AX-2025-020752SGNSGN-2504-P9721Kestrel2025-Q399.335.8089.0Supplier-supplied2MARGINAL
AX-2025-019911SWBSWB-2503-S5672Janoshik2025-Q399.363.1799.8Supplier-supplied0PASS
AX-2025-019904SWBSWB-2503-S5672Janoshik2025-Q399.102.9096.3Laboratory-retained0PASS
AX-2025-020888CPCCPC-2504-M1855Janoshik2025-Q397.835.33—Supplier-supplied0PASS
AX-2025-019912SWBSWB-2503-S5672Janoshik2025-Q399.313.19101.2Supplier-supplied0PASS
AX-2025-020890CPCCPC-2504-M1855PeptideMeter2025-Q398.334.80—Supplier-supplied0PASS
AX-2025-019908SWBSWB-2503-S5672Janoshik2025-Q399.302.9392.2Supplier-supplied0PASS
AX-2025-019910SWBSWB-2503-S5672Kestrel2025-Q399.463.53—Supplier-supplied1FAIL
AX-2025-019907SWBSWB-2503-S5672Nordanalyt2025-Q399.262.9590.3Supplier-supplied0PASS
AX-2025-020892CPCCPC-2504-M1855Nordanalyt2025-Q397.945.5199.0Supplier-supplied0PASS
AX-2024-005201SSASSA-2407-L6253Kestrel2024-Q398.971.1990.8Supplier-supplied0PASS
AX-2024-005200SSASSA-2407-L6253Janoshik2024-Q399.131.45102.7Supplier-supplied0PASS
AX-2024-005198SSASSA-2407-L6253Nordanalyt2024-Q398.231.77—Supplier-supplied0PASS
AX-2024-005199SSASSA-2407-L6253Janoshik2024-Q398.291.51—Supplier-supplied0PASS