AssayIndex
Neuroactive and cognitive peptides

Selank

TP-7 · Thr-Lys-Pro-Arg-Pro-Gly-Pro · C33H57N11O9 · monoisotopic 751.4402 Da. The index holds 102 assay reports on this compound across 24 batches from 19 suppliers.

102 reports24 batchesmedian 99.59 %index spec 99.0 %
Section 1

Analytical fingerprint

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

Selank is tuftsin extended with a Pro-Gly-Pro tail. Proline-rich sequences retain poorly and elute at 6.4 min, close to the injection front, so the same early-elution caution as KPV applies. Purity is high; water content runs 8–13 % and is the discriminating measurement.

Molecular formula
C33H57N11O9
Monoisotopic mass
751.4402Da
Average mass
751.88Da
Residues
7
Nominal retention (RG-2, 30 min)
6.42min
Retention window
0.25min
Counter-ion as usually shipped
acetate
Typical label claims
5 mg · 10 mg · 20 mg
Analytical difficulty (index scale)
0.80 — 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.

0418983781256716756 Selank6.42 min · 99.59 % 5.80 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 Selank trace on the index reference method RG-2, constructed from this page's own numbers: the main peak carries the index median purity of 99.59 % area at the nominal retention time of 6.42 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 102 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 99.59% n=102
Interquartile range 0.61pp n=102
Minimum 97.62% n=102
Maximum 99.93% n=102
Pass rate vs spec 83.3% n=102
Median recovery vs claim 99.4% n=53
Median water 8.14% n=102
Median |mass error| 2.8ppm n=86
010203092.093.094.095.096.097.098.099.0100.092.00–92.25 %: 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=197.75–98.00 %: n=098.00–98.25 %: n=498.25–98.50 %: n=498.50–98.75 %: n=098.75–99.00 %: n=899.00–99.25 %: n=1399.25–99.50 %: n=1399.50–99.75 %: n=2499.75–100.00 %: n=35median 99.59 Purity (% area) Reports
Figure 2. Purity distribution across all 102 Selank records. Dashed line is this compound's median (99.59 %); the solid vertical is the index acceptance specification for the neuroactive and cognitive peptides class (99.0 %). 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.

97.497.998.398.899.299.7100.1TFCTFC: Q1 99.16, median 99.24, Q3 99.39, n=14outlier 98.75outlier 99.83n=14TFSTFS: Q1 99.76, median 99.87, Q3 99.93, n=13n=13FGPFGP: Q1 99.85, median 99.89, Q3 99.93, n=11outlier 99.59n=11GGPepsGGPeps: Q1 99.37, median 99.62, Q3 99.69, n=9outlier 98.87n=9HJHJ: Q1 99.25, median 99.30, Q3 99.55, n=7n=7CPCCPC: Q1 98.89, median 98.95, Q3 99.11, n=7outlier 99.69n=7SGNSGN: Q1 98.14, median 98.28, Q3 98.31, n=7n=7GSPGSP: Q1 99.44, median 99.54, Q3 99.62, n=6n=6MKMMKM: Q1 99.65, median 99.74, Q3 99.83, n=6n=6HomopeptideHomopeptide: Q1 99.67, median 99.72, Q3 99.74, n=4outlier 99.57n=4ASYASY: Q1 99.63, median 99.83, Q3 99.88, n=3n=3QSCQSC: Q1 99.86, median 99.93, Q3 99.93, n=3n=3SWBSWB: Q1 99.22, median 99.24, Q3 99.25, n=2n=2SIGSIG: Q1 99.15, median 99.23, Q3 99.31, n=2n=2QYBQYB: Q1 99.70, median 99.78, Q3 99.86, n=2n=2WXTWXT: Q1 99.48, median 99.58, Q3 99.69, n=2n=2KPKP: Q1 97.72, median 97.81, Q3 97.91, n=2n=2 Purity (% area)
Figure 3. Selank 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
tuftsin fragment (−417 Da)-0.62-417.23598%0.120.95
diketopiperazine (−18 Da)+0.18-18.01189%0.060.55
acetyl adduct (+42 Da)+0.34+42.01184%0.090.67
des-Thr (−101 Da)-0.26-101.04883%0.101.40

Degradation pathways

  • diketopiperazine formation from Pro-rich sequence
  • no oxidative liability

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

Section 7

Quarterly coverage

QuarterReportsMedian purityRange
2024-Q10n<3—
2024-Q21n<3—
2024-Q3598.8697.62–99.79
2024-Q40n<3—
2025-Q1998.2898.06–99.50
2025-Q21199.1298.84–99.93
2025-Q32099.3199.02–99.83
2025-Q4799.2198.75–99.56
2026-Q12699.8199.31–99.93
2026-Q22199.7699.37–99.93
2026-Q32n<398.87–98.92

Quarter-by-quarter detail →

Section 8

Most recent records

The 25 most recent Selank records of 102.
ReportSupplierLotLabQuarterPurity %Water %Recovery %ProvenanceFlagsResult
AX-2026-042858GGPepsGGPE-2603-J2447VendorInvestigate2026-Q398.878.8599.4Buyer-sourced0FAIL
AX-2026-042859GGPepsGGPE-2603-J2447PeptideMeter2026-Q398.929.48103.5Buyer-sourced0FAIL
AX-2026-041759TFSTFS-{CAT}-1712Janoshik2026-Q299.938.13102.2Buyer-sourced0PASS
AX-2026-042912GGPepsGGPE-2601-J3130Janoshik2026-Q299.759.4489.7Buyer-sourced1MARGINAL
AX-2026-041760TFSTFS-{CAT}-1712Janoshik2026-Q299.827.70—Buyer-sourced0PASS
AX-2026-041752TFSTFS-{CAT}-1712Medutest2026-Q299.637.43—Buyer-sourced1FAIL
AX-2026-042915GGPepsGGPE-2601-J3130PeptideMeter2026-Q299.5310.03—Buyer-sourced0PASS
AX-2026-042910GGPepsGGPE-2601-J3130VendorInvestigate2026-Q299.629.21105.0Buyer-sourced0PASS
AX-2026-042911GGPepsGGPE-2601-J3130Kestrel2026-Q299.379.99—Buyer-sourced0PASS
AX-2026-041813ASYASY-{CAT}-2969PeptideMeter2026-Q299.938.25—Buyer-sourced0PASS
AX-2026-042913GGPepsGGPE-2601-J3130Kestrel2026-Q299.699.39—Laboratory-retained0PASS
AX-2026-041751TFSTFS-{CAT}-1712Janoshik2026-Q299.768.1989.9Buyer-sourced2MARGINAL
AX-2026-041763TFSTFS-{CAT}-1712PeptideMeter2026-Q299.878.20—Buyer-sourced0PASS
AX-2026-041755TFSTFS-{CAT}-1712VendorInvestigate2026-Q299.937.37104.5Buyer-sourced0PASS
AX-2026-041758TFSTFS-{CAT}-1712Janoshik2026-Q299.788.1097.6Buyer-sourced0PASS
AX-2026-042909GGPepsGGPE-2601-J3130Janoshik2026-Q299.7310.17—Buyer-sourced0PASS
AX-2026-041756TFSTFS-{CAT}-1712PeptideMeter2026-Q299.908.21103.7Buyer-sourced0PASS
AX-2026-042914GGPepsGGPE-2601-J3130Medutest2026-Q299.6610.0492.4Buyer-sourced0PASS
AX-2026-041762TFSTFS-{CAT}-1712Janoshik2026-Q299.757.24—Buyer-sourced0PASS
AX-2026-041757TFSTFS-{CAT}-1712Medutest2026-Q299.937.54—Buyer-sourced0PASS
AX-2026-041761TFSTFS-{CAT}-1712PeptideMeter2026-Q299.937.7991.8Buyer-sourced0PASS
AX-2026-041754TFSTFS-{CAT}-1712PeptideMeter2026-Q299.937.49—Buyer-sourced0PASS
AX-2026-041753TFSTFS-{CAT}-1712Janoshik2026-Q299.677.4892.6Buyer-sourced0PASS
AX-2026-041625FGPFGP-2511-D8133Medutest2026-Q199.766.3898.2Buyer-sourced0PASS
AX-2026-041626FGPFGP-2511-D8133PeptideMeter2026-Q199.596.1295.2Buyer-sourced0PASS