AX-2025-020423 · Melanotan II · KP lot KP-2508-J4716

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.

Parameter	Method	Result	Unit	Index spec
Purity	RP-HPLC, 15 min gradient, 214 nm	98.29	% area	≥ 98.5	FAIL
Total impurities	RP-HPLC, sum of reported peaks	1.71	% area	≤ 1.5	FAIL
Largest single impurity	RP-HPLC — linear (open-lactam) precursor (+18 Da)	0.83	% area	≤ 1.00	PASS
Identity — theoretical monoisotopic mass	calculated from molecular formula	1023.5402	Da	—	NOT TESTED
Identity — observed monoisotopic mass	LC-MS, unit resolution (single quadrupole)	1023.5411	Da	—	NOT TESTED
Mass accuracy	observed vs theoretical	+0.9	ppm	± 15	PASS
Total peptide content	by difference from the gravimetric mass balance	88.32	%w/w	—	NOT TESTED
Target-compound content	total peptide content × purity	86.81	%w/w	—	NOT TESTED
Gross fill (as weighed)	five-place balance, under nitrogen	10.81	mg	10 mg declared	NOT TESTED
Recovered target peptide	gross fill × target content	9.384	mg	10 mg claim	NOT TESTED
Recovery against label claim	recovered ÷ claim	93.8	%	90.0 – 110.0	PASS
Water content	Karl Fischer, coulometric, duplicate	6.79	%	≤ 8.0	PASS
Counter-ion (acetate)	anion-exchange ion chromatography	3.94	%	≤ 10.0	PASS
Residual solvent + inorganic residue	estimated — see /methods/residual-solvents-q3c/	0.95	%	—	NOT TESTED
Endotoxin	not ordered on this submission	not determined	—	≤ 5.0	NOT TESTED
Sterility	not ordered on this submission	not determined	—	no growth	NOT TESTED
Appearance	visual, diffuse light, black and white background	White cake, partial shrinkage from vial wall	—	white to off-white intact cake	FAIL
Reconstitution clarity	reconstituted per submitter procedure	Clear, colourless, no visible particulates	—	clear, no visible particulates	PASS
pH (reconstituted, 1 mg/mL)	potentiometric, two-point calibration	4.12	—	2.5 – 8.0	PASS
Retention time (observed)	RP-HPLC, 15 min gradient	5.26	min	5.31 ± 0.25 (normalised)	PASS
Peak asymmetry (10 % height)	Ph. Eur. 2.2.46	1.10	—	0.80 – 1.50	PASS
Plate count, main peak	N = 5.54 (t/w½)²	82,729	—	≥ 20,000	PASS
Resolution to nearest impurity	vs [L-Phe7]-diastereomer	1.07	—	no index criterion	REPORTED

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.

Figure 1. RP-HPLC trace, 15 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 82,729, and skew follows the reported asymmetry factor of 1.10. 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 0.83 % impurity against a 98.29 % main peak is a line two pixels tall; the main peak runs off-scale there by design.

#	Peak	RT	Area (µV·s)	% area	Δ mass (Da)
1	Melanotan II — main peak	5.26	4,777,199	98.29	—
2	linear (open-lactam) precursor (+18 Da)	4.89	40,341	0.83	+18.011
3	[L-Phe7]-diastereomer	5.18	26,246	0.54	0.000
4	des-acetyl MT-II (−42 Da)	5.02	9,721	0.20	-42.011
5	oxidised Trp (+16 Da)	5.08	3,888	0.08	+15.995
6	MT-II dimer (head-to-tail)	6.43	2,916	0.06	+1023.540
Closure check — purity + Σ impurities				100.00	CLOSES

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.

Figure 2. ESI charge-state envelope, unit-resolution instrument. Sticks are placed at m/z = (M + z × 1.007276)/z for the observed neutral mass of 1023.5411 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.

Charge	Theoretical m/z	Observed m/z	Δ m/z	Rel. abundance (%)
3+	342.1873	342.1876	0.0003	8.7
2+	512.7774	512.7778	0.0004	59.7
1+	1024.5475	1024.5484	0.0009	100.0

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.

Component	Determination	%w/w of cake
Water	Karl Fischer	6.79
Counter-ion (acetate)	ion chromatography	3.94
Residual solvent + inorganic residue	estimated	0.95
Total peptide content	by difference	88.32
Total		100.00 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.

Figure	Supplier COA	This report	Index note
Purity (% area)	98.21	98.29	divergence -0.15 pp vs batch median
Total impurities (% area)	not stated	1.71
Largest single impurity (% area)	not stated	0.83
Water (%)	5.5	6.79
Counter-ion (%)	not stated	3.94
Peptide content (%w/w)	not stated	88.32
Endotoxin (EU/mg)	0.31	not determined
Method stated on certificate	YES	—	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, 10 d since original receipt) → re-assay.
Assay date: 03 Aug 2025
Submitted to the index: 29 Aug 2025
Laboratory: Kestrel Bioanalytical, Melbourne, Australia
Method basis: 15 min gradient · unit-resolution MS
Verification status: METHOD LIMITED

What this report does not establish

That the compound is not a near-isobaric alternative. Identity was confirmed at unit mass resolution, which cannot exclude species differing by 1 or 2 Da. The specific alternatives not excluded are named in the identity block above.
That mass-identical impurities are absent. The gradient used is shorter than the index reference method and does not resolve the diastereomers named in the compound fingerprint. The purity figure is an upper bound.
That the material is free of bacterial endotoxin. Endotoxin was not measured. No chromatographic result bears on it.
That the material is sterile. Sterility was not tested.
That any other vial in the same lot has the same composition. One vial was tested. Within-lot vial-to-vial variation in this index has a median of 0.28 pp and a 90th percentile of 0.74 pp.
That any other lot from the same supplier has the same composition. Batch-to-batch variation is larger than within-batch variation for every supplier here.
That the material is suitable for administration to a human or an animal. These are research compounds. No result on this site is a safety assessment and the index takes no position on use.
That the material was manufactured by the supplier that sold it. Contract synthesis is normal in this market and twenty-nine batches in the index fingerprint to a bulk from a different company than the one named on the label.

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 KP-2508-J4716 n=11

Report	Lot	Lab	Quarter	Purity %	Water %	Recovery %	Provenance	Flags	Result
AX-2025-020414	KP-2508-J4716	Janoshik	2025-Q3	97.61	6.52	—	Buyer-sourced	1	FAIL
AX-2025-020415	KP-2508-J4716	Kestrel	2025-Q3	98.24	6.52	96.3	Supplier-supplied	1	FAIL
AX-2025-020416	KP-2508-J4716	Janoshik	2025-Q3	98.43	6.74	—	Supplier-supplied	1	FAIL
AX-2025-020417	KP-2508-J4716	Janoshik	2025-Q3	98.50	6.48	99.0	Supplier-supplied	1	MARGINAL
AX-2025-020418	KP-2508-J4716	Medutest	2025-Q3	98.40	6.66	96.7	Supplier-supplied	1	FAIL
AX-2025-020419	KP-2508-J4716	Janoshik	2025-Q3	98.82	6.76	88.9	Supplier-supplied	2	MARGINAL
AX-2025-020420	KP-2508-J4716	PeptideMeter	2025-Q3	98.09	6.51	97.0	Supplier-supplied	1	FAIL
AX-2025-020421	KP-2508-J4716	Janoshik	2025-Q3	98.39	6.59	—	Supplier-supplied	1	FAIL
AX-2025-020422	KP-2508-J4716	VendorInvestigate	2025-Q3	97.64	6.74	—	Buyer-sourced	1	FAIL
AX-2025-020424	KP-2508-J4716	Janoshik	2025-Q3	98.36	6.47	90.8	Supplier-supplied	1	FAIL

Batch rollup and reproducibility assessment →

Cross-sections

Other recent Melanotan II records in the index.
Report	Supplier	Lot	Lab	Quarter	Purity %	Water %	Recovery %	Provenance	Flags	Result
AX-2026-042648	GGPeps	GGPE-2603-P8735	Janoshik	2026-Q3	99.10	6.97	—	Supplier-supplied	4	MARGINAL
AX-2026-042479	SWB	SWB-2603-A5707	Janoshik	2026-Q3	99.16	3.67	94.5	Supplier-supplied	1	MARGINAL
AX-2026-042481	SWB	SWB-2603-A5707	Medutest	2026-Q3	98.95	3.37	90.8	Supplier-supplied	1	MARGINAL
AX-2026-042650	GGPeps	GGPE-2603-P8735	Medutest	2026-Q3	99.86	6.49	—	Supplier-supplied	3	MARGINAL
AX-2026-042483	SWB	SWB-2603-A5707	Janoshik	2026-Q3	99.38	3.73	107.2	Supplier-supplied	1	MARGINAL
AX-2026-042651	GGPeps	GGPE-2603-P8735	PeptideMeter	2026-Q3	99.53	7.04	90.7	Supplier-supplied	4	MARGINAL
AX-2026-042478	SWB	SWB-2603-A5707	VendorInvestigate	2026-Q3	98.73	4.34	—	Buyer-sourced	1	MARGINAL
AX-2026-042482	SWB	SWB-2603-A5707	Janoshik	2026-Q3	99.22	4.66	—	Supplier-supplied	1	MARGINAL

Other recent KP records in the index.
Report	Compound	Lot	Lab	Quarter	Purity %	Water %	Recovery %	Provenance	Flags	Result
AX-2026-043029	Retatrutide	KP-2607-H5219	Medutest	2026-Q3	95.45	5.71	—	Supplier-supplied	2	FAIL
AX-2026-043030	Retatrutide	KP-2607-H5219	Kestrel	2026-Q3	95.97	6.95	97.1	Supplier-supplied	2	FAIL
AX-2026-043106	Tirzepatide	KP-2608-D5921	PeptideMeter	2026-Q3	98.90	5.45	105.4	Supplier-supplied	2	MARGINAL
AX-2026-043108	Tirzepatide	KP-2608-D5921	Janoshik	2026-Q3	99.70	5.45	—	Supplier-supplied	2	MARGINAL
AX-2026-043039	Retatrutide	KP-2607-H5219	Janoshik	2026-Q3	96.14	5.62	—	Supplier-supplied	2	FAIL
AX-2026-043100	Tirzepatide	KP-2608-D5921	VendorInvestigate	2026-Q3	98.27	5.31	94.4	Buyer-sourced	2	MARGINAL
AX-2026-043090	Ipamorelin	KP-2606-D5887	Janoshik	2026-Q3	98.18	3.07	101.2	Laboratory-retained	1	FAIL
AX-2026-043028	Retatrutide	KP-2607-H5219	Janoshik	2026-Q3	96.52	6.09	—	Supplier-supplied	2	MARGINAL