AssayIndex

AX-2026-043436

Melanotan II · 10 mg declared · WuXi TIDES (WuXi AppTec Testing Division) · lot WXT-2511-P5160

MARGINALVERIFIED
Report ID
AX-2026-043436
Compound
Melanotan II
Compound class
Melanocortin-receptor peptides
Supplier
WXT — WuXi TIDES (WuXi AppTec Testing Division)
Batch / lot
WXT-2511-P5160
Declared label claim
10mg
Laboratory
Janoshik Analytical
Assay date
17 Mar 2026
Submitted
08 Apr 2026
Quarter
2026-Q1
Submitter
c.ilunga
Sample provenance
Laboratory-retained
Section 1

Results

Measured against the index acceptance specification for the melanocortin-receptor peptides class. A specification is a decision the index made; a result is a measurement. See where each threshold came from.

ParameterMethodResultUnitIndex spec
PurityRP-HPLC, 30 min gradient, 214 nm98.91% area≥ 98.5PASS
Total impuritiesRP-HPLC, sum of reported peaks1.09% area≤ 1.5PASS
Largest single impurityRP-HPLC — [L-Phe7]-diastereomer0.61% area≤ 1.00PASS
Identity — theoretical monoisotopic masscalculated from molecular formula1023.5402Da—NOT TESTED
Identity — observed monoisotopic massLC-MS, high resolution (ESI-TOF/QTOF)1023.5399Da—NOT TESTED
Mass accuracyobserved vs theoretical-0.3ppm± 15PASS
Total peptide contentby difference from the gravimetric mass balance90.76%w/w—NOT TESTED
Target-compound contenttotal peptide content × purity89.77%w/w—NOT TESTED
Gross fill (as weighed)five-place balance, under nitrogen11.36mg10 mg declaredNOT TESTED
Recovered target peptidegross fill × target content10.198mg10 mg claimNOT TESTED
Recovery against label claimrecovered ÷ claim102.0%90.0 – 110.0PASS
Water contentKarl Fischer, coulometric, duplicate4.39%≤ 8.0PASS
Counter-ion (acetate)anion-exchange ion chromatography3.97%≤ 10.0PASS
Residual solvent + inorganic residueestimated — see /methods/residual-solvents-q3c/0.88%—NOT TESTED
Endotoxinkinetic chromogenic LAL0.56EU/mg≤ 5.0PASS
Sterilitymembrane filtration, USP <71>, 14 dNo growth at 14 d—no growthPASS
Appearancevisual, diffuse light, black and white backgroundWhite cake, partial shrinkage from vial wall—white to off-white intact cakeFAIL
Reconstitution clarityreconstituted per submitter procedureClear, colourless, no visible particulates—clear, no visible particulatesPASS
pH (reconstituted, 1 mg/mL)potentiometric, two-point calibration5.61—2.5 – 8.0PASS
Retention time (observed)RP-HPLC, 30 min gradient9.93min9.84 ± 0.25 (normalised)PASS
Peak asymmetry (10 % height)Ph. Eur. 2.2.460.97—0.80 – 1.50PASS
Plate count, main peakN = 5.54 (t/w½)²74,929—≥ 20,000PASS
Resolution to nearest impurityvs [L-Phe7]-diastereomer1.08—no index criterionREPORTED
Section 2

Chromatogram and peak integration

The figure is drawn from the table. It is not an independent illustration — if a number in the table changed, the trace would change with it.

032046408961312817 Melanotan II9.93 min · 98.91 % 9.7712.28 same trace · ×100 vertical expansion, baseline-corrected · main peak off-scale reporting threshold 0.05 % area 05101520253035 Retention time (min) Response (mAU)
Figure 1. RP-HPLC trace, 30 min gradient, 214 nm. Drawn from the peak-integration table below: peak positions are the reported retention times, peak areas are the reported area percentages, peak widths follow the reported plate count of 74,929, and skew follows the reported asymmetry factor of 0.97. Baseline noise is seeded from the report ID and is illustrative. The lower panel is the same trace at a stated vertical expansion with the slow gradient drift subtracted, because at full scale a 0.61 % impurity against a 98.91 % main peak is a line two pixels tall; the main peak runs off-scale there by design.
#PeakRTArea (µV·s)% areaΔ mass (Da)
1Melanotan II — main peak9.934,807,33398.91—
2[L-Phe7]-diastereomer9.7729,6480.610.000
3linear (open-lactam) precursor (+18 Da)9.1911,1790.23+18.011
4oxidised Trp (+16 Da)9.576,3180.13+15.995
5MT-II dimer (head-to-tail)12.282,9160.06+1023.540
6des-acetyl MT-II (−42 Da)9.452,9160.06-42.011
Closure check — purity + Σ impurities 100.00CLOSES

Reporting threshold 0.05 % area. Peaks below it are not reported and are therefore excluded from the total, which overstates purity by their sum — see peak integration.

Section 3

Mass spectrum and identity

Theoretical monoisotopic mass 1023.5402 Da, computed from C50H69N15O9. All ppm figures on this site are against monoisotopic values — see why that matters.

025507510025040055070085010001150 [M+1H]1+1024.55[M+2H]2+512.78 m/z Relative abundance (%)
Figure 2. ESI charge-state envelope, high-resolution instrument. Sticks are placed at m/z = (M + z × 1.007276)/z for the observed neutral mass of 1023.5399 Da. Sodium (+21.982/z) and potassium (+37.956/z) adducts are shown where the parent charge state exceeds 25 % relative abundance; they are adducts of the same molecule and are not impurities.
ChargeTheoretical m/zObserved m/zΔ m/zRel. abundance (%)
3+342.1873342.1872-0.00018.7
2+512.7774512.7772-0.000251.7
1+1024.54751024.5472-0.0003100.0
Section 4

Gravimetric mass balance

Water, counter-ion, residual and total peptide content are exhaustive and mutually exclusive categories. They must account for 100 % of the cake mass. The index closes this to within 0.02 pp and the build asserts it.

ComponentDetermination%w/w of cake
WaterKarl Fischer4.39
Counter-ion (acetate)ion chromatography3.97
Residual solvent + inorganic residueestimated0.88
Total peptide contentby difference90.76
Total100.00 CLOSES

Supplier certificate, as declared

The supplier's own figures for this lot, beside the independent measurement. Divergence is assessed against the batch median, not against this single report — see rule AX-R05.

FigureSupplier COAThis reportIndex note
Purity (% area)100.098.91divergence +0.91 pp vs batch median
Total impurities (% area)0.001.09
Largest single impurity (% area)not stated0.61
Water (%)not stated4.39
Counter-ion (%)5.33.97
Peptide content (%w/w)90.690.76
Endotoxin (EU/mg)not stated0.56
Method stated on certificateYES—column, gradient and wavelength given
Section 5

Provenance and caveats

Where a sample came from changes the weight of the evidence. The index treats it as a first-class field.

Sample provenance
Laboratory-retained
Evidentiary weight
Provenance documented, selection uncontrolled.
Chain of custody
Laboratory retained sample (−20 °C, 32 d since original receipt) → re-assay.
Assay date
17 Mar 2026
Submitted to the index
08 Apr 2026
Laboratory
Janoshik Analytical, Ostrava, Czechia
Method basis
30 min gradient · high-resolution MS
Verification status
VERIFIED
Section 6

Annotations

No annotations on this record. Annotations are short signed technical comments from index contributors; see how to contribute.

Section 7

Related records

Same batch — lot WXT-2511-P5160 n=6

ReportLotLabQuarterPurity %Water %Recovery %ProvenanceFlagsResult
AX-2026-043435WXT-2511-P5160PeptideMeter2026-Q199.034.3891.2Supplier-supplied3MARGINAL
AX-2026-043437WXT-2511-P5160Janoshik2026-Q199.014.7398.2Buyer-sourced2MARGINAL
AX-2026-043438WXT-2511-P5160Janoshik2026-Q199.804.51105.3Supplier-supplied2MARGINAL
AX-2026-043439WXT-2511-P5160Kestrel2026-Q199.934.76—Supplier-supplied2MARGINAL
AX-2026-043440WXT-2511-P5160Janoshik2026-Q199.154.51—Supplier-supplied3FAIL

Cross-sections

Other recent Melanotan II records in the index.
ReportSupplierLotLabQuarterPurity %Water %Recovery %ProvenanceFlagsResult
AX-2026-042648GGPepsGGPE-2603-P8735Janoshik2026-Q399.106.97—Supplier-supplied4MARGINAL
AX-2026-042479SWBSWB-2603-A5707Janoshik2026-Q399.163.6794.5Supplier-supplied1MARGINAL
AX-2026-042481SWBSWB-2603-A5707Medutest2026-Q398.953.3790.8Supplier-supplied1MARGINAL
AX-2026-042650GGPepsGGPE-2603-P8735Medutest2026-Q399.866.49—Supplier-supplied3MARGINAL
AX-2026-042483SWBSWB-2603-A5707Janoshik2026-Q399.383.73107.2Supplier-supplied1MARGINAL
AX-2026-042651GGPepsGGPE-2603-P8735PeptideMeter2026-Q399.537.0490.7Supplier-supplied4MARGINAL
AX-2026-042478SWBSWB-2603-A5707VendorInvestigate2026-Q398.734.34—Buyer-sourced1MARGINAL
AX-2026-042482SWBSWB-2603-A5707Janoshik2026-Q399.224.66—Supplier-supplied1MARGINAL
Other recent WXT records in the index.
ReportCompoundLotLabQuarterPurity %Water %Recovery %ProvenanceFlagsResult
AX-2026-043488PramlintideWXT-2603-D6052Janoshik2026-Q397.874.37—Supplier-supplied1MARGINAL
AX-2026-043406SemaglutideWXT-2604-C4728Janoshik2026-Q397.244.65—Supplier-supplied1MARGINAL
AX-2026-043421SermorelinWXT-2608-P4867Janoshik2026-Q398.153.09—Supplier-supplied0PASS
AX-2026-043420SermorelinWXT-2608-P4867Medutest2026-Q398.623.0796.4Supplier-supplied0PASS
AX-2026-043423SermorelinWXT-2608-P4867Janoshik2026-Q398.283.8698.5Buyer-sourced0PASS
AX-2026-043401SemaglutideWXT-2604-C4728Medutest2026-Q397.704.7891.5Supplier-supplied1MARGINAL
AX-2026-043400SemaglutideWXT-2604-C4728Nordanalyt2026-Q396.864.11106.4Laboratory-retained1FAIL
AX-2026-043422SermorelinWXT-2608-P4867Medutest2026-Q398.353.59—Supplier-supplied1MARGINAL