AssayIndex
Melanocortin-receptor peptides

Afamelanotide

NDP-α-MSH · Melanotan I · Scenesse · C78H111N21O19 · monoisotopic 1645.8474 Da. The index holds 53 assay reports on this compound across 11 batches from 6 suppliers.

53 reports11 batchesmedian 99.28 %index spec 98.0 %
Section 1

Analytical fingerprint

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

Afamelanotide is a linear 13-mer, not a cyclic peptide, and is often sold as "Melanotan I" alongside the cyclic MT-II under names that imply they are the same series. They are not; the masses are 623 Da apart. Afamelanotide's dominant impurity is Met sulfoxide and its levels are the highest of the melanocortin group, which is consistent with the compound's known photosensitivity.

Molecular formula
C78H111N21O19
Monoisotopic mass
1645.8474Da
Average mass
1646.85Da
Residues
13
Nominal retention (RG-2, 30 min)
10.86min
Retention window
0.30min
Counter-ion as usually shipped
acetate
Typical label claims
10 mg
Analytical difficulty (index scale)
0.95 — 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.

02469493774069875 Afamelanotide10.86 min · 99.28 % 10.42 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 Afamelanotide trace on the index reference method RG-2, constructed from this page's own numbers: the main peak carries the index median purity of 99.28 % area at the nominal retention time of 10.86 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 53 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 99.28% n=53
Interquartile range 1.29pp n=53
Minimum 97.04% n=53
Maximum 99.93% n=53
Pass rate vs spec 86.8% n=53
Median recovery vs claim 100.9% n=29
Median water 4.39% n=53
Median |mass error| 2.2ppm n=43
05101592.093.094.095.096.097.098.099.0100.092.00–92.25 %: 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=197.25–97.50 %: n=197.50–97.75 %: n=297.75–98.00 %: n=398.00–98.25 %: n=498.25–98.50 %: n=198.50–98.75 %: n=398.75–99.00 %: n=299.00–99.25 %: n=999.25–99.50 %: n=299.50–99.75 %: n=999.75–100.00 %: n=16median 99.28 Purity (% area) Reports
Figure 2. Purity distribution across all 53 Afamelanotide records. Dashed line is this compound's median (99.28 %); the solid vertical is the index acceptance specification for the melanocortin-receptor peptides class (98.0 %). 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.

96.897.497.998.599.099.6100.2WWBWWB: Q1 99.24, median 99.53, Q3 99.77, n=15n=15QSCQSC: Q1 99.82, median 99.93, Q3 99.93, n=12outlier 99.55outlier 99.65n=12BCHBCH: Q1 97.74, median 97.97, Q3 98.16, n=9n=9SGNSGN: Q1 98.01, median 98.43, Q3 98.83, n=6n=6HomopeptideHomopeptide: Q1 99.05, median 99.12, Q3 99.47, n=6n=6TFCTFC: Q1 98.90, median 99.01, Q3 99.52, n=5n=5 Purity (% area)
Figure 3. Afamelanotide 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 (−42 Da)-0.52-42.011100%0.110.94
Met sulfoxide (+16 Da)-0.44+15.99592%0.221.38
native α-MSH (−32 Da)-0.66-32.03783%0.170.35
oxidised Trp (+16 Da)-0.38+15.99574%0.152.11

Degradation pathways

  • Met4 oxidation
  • acetyl loss

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.

Afamelanotide is approved in the EU and United States for erythropoietic protoporphyria.

Section 7

Quarterly coverage

QuarterReportsMedian purityRange
2024-Q11798.2497.39–99.93
2024-Q20n<3—
2024-Q31299.9399.55–99.93
2024-Q4699.5399.20–99.93
2025-Q1498.9698.58–99.28
2025-Q20n<3—
2025-Q30n<3—
2025-Q4498.1197.04–98.56
2026-Q1699.1298.74–99.93
2026-Q22n<399.52–99.92
2026-Q32n<398.92–99.19

Quarter-by-quarter detail →

Section 8

Most recent records

The 25 most recent Afamelanotide records of 53.
ReportSupplierLotLabQuarterPurity %Water %Recovery %ProvenanceFlagsResult
AX-2026-043215SGNSGN-2602-Y9898PeptideMeter2026-Q398.923.40—Supplier-supplied1MARGINAL
AX-2026-043214SGNSGN-2602-Y9898Janoshik2026-Q399.193.41106.9Supplier-supplied1MARGINAL
AX-2026-042064TFCTFC-2601-L7201Medutest2026-Q299.923.89105.0Supplier-supplied0PASS
AX-2026-042063TFCTFC-2601-L7201Janoshik2026-Q299.524.63—Supplier-supplied0PASS
AX-2026-042224HomopeptideHOMO-2511-V9695PeptideMeter2026-Q199.935.28104.5Supplier-supplied0PASS
AX-2026-042202HomopeptideHOMO-2509-K9821Janoshik2026-Q199.035.0499.1Supplier-supplied1MARGINAL
AX-2026-042200HomopeptideHOMO-2509-K9821Janoshik2026-Q199.124.6595.4Supplier-supplied1MARGINAL
AX-2026-042203HomopeptideHOMO-2509-K9821Janoshik2026-Q199.594.60100.0Supplier-supplied2FAIL
AX-2026-042204HomopeptideHOMO-2509-K9821Janoshik2026-Q199.124.88104.2Supplier-supplied1MARGINAL
AX-2026-042201HomopeptideHOMO-2509-K9821PeptideMeter2026-Q198.745.50—Supplier-supplied1MARGINAL
AX-2025-020740SGNSGN-2510-R8898Medutest2025-Q498.565.02101.2Supplier-supplied1MARGINAL
AX-2025-020739SGNSGN-2510-R8898VendorInvestigate2025-Q497.045.1789.4Buyer-sourced1FAIL
AX-2025-020738SGNSGN-2510-R8898Nordanalyt2025-Q497.925.10—Buyer-sourced0FAIL
AX-2025-020737SGNSGN-2510-R8898Janoshik2025-Q498.294.71103.4Supplier-supplied1MARGINAL
AX-2025-018524WWBWWB-2408-E4076Nordanalyt2025-Q199.281.84—Supplier-supplied0PASS
AX-2025-019265TFCTFC-2502-Y6610Janoshik2025-Q198.904.59104.3Supplier-supplied0PASS
AX-2025-019267TFCTFC-2502-Y6610Janoshik2025-Q199.014.82—Supplier-supplied0PASS
AX-2025-019266TFCTFC-2502-Y6610Janoshik2025-Q198.584.81—Laboratory-retained0PASS
AX-2024-004139WWBWWB-2406-Y1595Medutest2024-Q499.535.07—Supplier-supplied0PASS
AX-2024-004138WWBWWB-2406-Y1595Nordanalyt2024-Q499.524.3992.7Supplier-supplied0PASS
AX-2024-004137WWBWWB-2406-Y1595Janoshik2024-Q499.544.3494.1Supplier-supplied0PASS
AX-2024-004136WWBWWB-2406-Y1595Janoshik2024-Q499.934.91—Supplier-supplied0PASS
AX-2024-004140WWBWWB-2406-Y1595Nordanalyt2024-Q499.204.59—Supplier-supplied0PASS
AX-2024-004135WWBWWB-2406-Y1595Janoshik2024-Q499.204.95107.5Laboratory-retained0PASS
AX-2024-004440QSCQSC-2407-F9884Janoshik2024-Q399.932.8991.9Supplier-supplied0PASS