AX-2026-043598 · Melanotan II · WXT lot WXT-2511-P5567

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	99.93	% area	≥ 98.5	PASS
Total impurities	RP-HPLC, sum of reported peaks	0.07	% area	≤ 1.5	PASS
Largest single impurity	RP-HPLC — oxidised Trp (+16 Da)	0.04	% 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)	1023.5446	Da	—	NOT TESTED
Mass accuracy	observed vs theoretical	+4.3	ppm	± 15	PASS
Total peptide content	by difference from the gravimetric mass balance	90.15	%w/w	—	NOT TESTED
Target-compound content	total peptide content × purity	90.09	%w/w	—	NOT TESTED
Gross fill (as weighed)	five-place balance, under nitrogen	10.18	mg	10 mg declared	NOT TESTED
Recovered target peptide	gross fill × target content	9.171	mg	10 mg claim	NOT TESTED
Recovery against label claim	recovered ÷ claim	91.7	%	90.0 – 110.0	PASS
Water content	Karl Fischer, coulometric, duplicate	4.29	%	≤ 8.0	PASS
Counter-ion (acetate)	anion-exchange ion chromatography	4.68	%	≤ 10.0	PASS
Residual solvent + inorganic residue	estimated — see /methods/residual-solvents-q3c/	0.88	%	—	NOT TESTED
Endotoxin	kinetic chromogenic LAL	0.53	EU/mg	≤ 5.0	PASS
Sterility	not ordered on this submission	not determined	—	no growth	NOT TESTED
Appearance	visual, diffuse light, black and white background	Off-white lyophilised cake, intact	—	white to off-white intact cake	PASS
Reconstitution clarity	reconstituted per submitter procedure	Clear after 90 s gentle swirling, no particulates	—	clear, no visible particulates	PASS
pH (reconstituted, 1 mg/mL)	potentiometric, two-point calibration	5.87	—	2.5 – 8.0	PASS
Retention time (observed)	RP-HPLC, 15 min gradient	5.37	min	5.31 ± 0.25 (normalised)	PASS
Peak asymmetry (10 % height)	Ph. Eur. 2.2.46	1.23	—	0.80 – 1.50	PASS
Plate count, main peak	N = 5.54 (t/w½)²	72,746	—	≥ 20,000	PASS
Resolution to nearest impurity	vs oxidised Trp (+16 Da)	2.21	—	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 72,746, and skew follows the reported asymmetry factor of 1.23. 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 0.04 % impurity against a 99.93 % 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	5.37	4,856,908	99.93	—
2	oxidised Trp (+16 Da)	5.19	1,944	0.04	+15.995
3	linear (open-lactam) precursor (+18 Da)	5.00	1,458	0.03	+18.011
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 1023.5446 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	342.1888	0.0015	7.8
2+	512.7774	512.7796	0.0022	54.1
1+	1024.5475	1024.5519	0.0044	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	4.29
Counter-ion (acetate)	ion chromatography	4.68
Residual solvent + inorganic residue	estimated	0.88
Total peptide content	by difference	90.15
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)	99.33	99.93	divergence -0.13 pp vs batch median
Total impurities (% area)	-0.16	0.07
Largest single impurity (% area)	not stated	0.04
Water (%)	not stated	4.29
Counter-ion (%)	not stated	4.68
Peptide content (%w/w)	91.7	90.15
Endotoxin (EU/mg)	not stated	0.53
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: Buyer-sourced
Evidentiary weight: Strongest available evidence in this index.
Chain of custody: Retail purchase → submitter (−20 °C, 17 d) → laboratory (courier, dry ice, 2 d) → assay.
Assay date: 06 Mar 2026
Submitted to the index: 10 Mar 2026
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 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 4

Signed technical comments from index contributors. Not a discussion forum — annotations question or contextualise the result, and the data team replies where a reply is warranted.

baseline_noise10 Mar 2026

Baseline on this trace is flat enough that the reporting threshold is doing real work rather than hiding peaks in noise. That is a precondition for believing 99.93 % and it is not always met.

area_percent10 Mar 2026

Area percent assumes unit response factors across every species present. At 99.93 % the assumption barely matters — there is not enough impurity for a response-factor error to move the figure by a tenth.

buyer_sourced10 Mar 2026

Ordering under an unremarkable name and address is the whole method. It requires no cooperation from anybody and it produces the strongest evidence this index holds.

dedupe_logic10 Mar 2026

Two retail purchases of the same lot from different buyers are genuinely independent. Two aliquots of one purchase are not, and the index does not treat them as such.

Section 7

Related records

Same batch — lot WXT-2511-P5567 n=8

Report	Lot	Lab	Quarter	Purity %	Water %	Recovery %	Provenance	Flags	Result
AX-2026-043594	WXT-2511-P5567	Janoshik	2026-Q1	99.38	4.20	—	Supplier-supplied	1	MARGINAL
AX-2026-043595	WXT-2511-P5567	Janoshik	2026-Q1	99.93	4.05	100.6	Supplier-supplied	1	MARGINAL
AX-2026-043596	WXT-2511-P5567	Janoshik	2026-Q1	99.54	4.20	—	Laboratory-retained	1	MARGINAL
AX-2026-043597	WXT-2511-P5567	Nordanalyt	2026-Q1	99.28	4.15	88.8	Buyer-sourced	2	MARGINAL
AX-2026-043599	WXT-2511-P5567	Janoshik	2026-Q1	99.13	4.10	100.1	Buyer-sourced	1	MARGINAL
AX-2026-043600	WXT-2511-P5567	Janoshik	2026-Q1	99.45	4.41	98.7	Buyer-sourced	1	MARGINAL
AX-2026-043601	WXT-2511-P5567	Nordanalyt	2026-Q1	99.46	3.63	—	Laboratory-retained	1	MARGINAL

Batch rollup and reproducibility assessment →

Cross-sections

Other recent Melanotan II records in the index.
Report	Supplier	Lot	Lab	Quarter	Purity %	Water %	Recovery %	Provenance	Result
AX-2026-042691	SWB	SWB-2603-A7409	Kestrel	2026-Q3	99.60	4.39	90.5	Laboratory-retained	PASS
AX-2026-042692	SWB	SWB-2603-A7409	Janoshik	2026-Q3	99.73	3.66	94.9	Supplier-supplied	PASS
AX-2026-042687	SWB	SWB-2603-A7409	Nordanalyt	2026-Q3	99.05	4.33	—	Buyer-sourced	PASS
AX-2026-042693	SWB	SWB-2603-A7409	Janoshik	2026-Q3	99.93	4.63	—	Supplier-supplied	PASS
AX-2026-042686	SWB	SWB-2603-A7409	PeptideMeter	2026-Q3	99.69	4.52	—	Buyer-sourced	PASS
AX-2026-042685	SWB	SWB-2603-A7409	Janoshik	2026-Q3	99.03	4.35	—	Buyer-sourced	PASS
AX-2026-042694	SWB	SWB-2603-A7409	PeptideMeter	2026-Q3	99.21	3.84	—	Buyer-sourced	PASS
AX-2026-042684	SWB	SWB-2603-A7409	Janoshik	2026-Q3	99.01	3.41	—	Buyer-sourced	PASS

Other recent WXT records in the index.
Report	Compound	Lot	Lab	Quarter	Purity %	Water %	Recovery %	Provenance	Flags	Result
AX-2026-043651	Pramlintide	WXT-2603-D6459	PeptideMeter	2026-Q3	98.21	4.97	101.6	Buyer-sourced	1	MARGINAL
AX-2026-043531	Leuprolide	WXT-2604-K4483	Medutest	2026-Q3	99.00	5.03	—	Buyer-sourced	0	PASS
AX-2026-043561	Semaglutide	WXT-2604-C5135	Janoshik	2026-Q3	96.96	4.22	91.3	Buyer-sourced	0	FAIL
AX-2026-043627	L-Glutathione (reduced)	WXT-2605-B5720	Janoshik	2026-Q3	97.96	6.08	92.3	Buyer-sourced	1	FAIL
AX-2026-043564	Semaglutide	WXT-2604-C5135	Janoshik	2026-Q3	97.15	4.44	104.7	Buyer-sourced	0	PASS
AX-2026-043533	Leuprolide	WXT-2604-K4483	PeptideMeter	2026-Q3	99.89	4.94	—	Supplier-supplied	0	PASS
AX-2026-043624	L-Glutathione (reduced)	WXT-2605-B5720	Nordanalyt	2026-Q3	98.18	6.95	105.3	Buyer-sourced	2	FAIL
AX-2026-043556	Semaglutide	WXT-2604-C5135	PeptideMeter	2026-Q3	97.56	4.35	89.6	Buyer-sourced	1	MARGINAL