AX-2025-019109 · Retatrutide · GSP lot GSP-2411-B2857

Section 1

Results

Measured against the index acceptance specification for the incretin analogues and co-agonists 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	97.98	% area	≥ 96.5	PASS
Total impurities	RP-HPLC, sum of reported peaks	2.02	% area	≤ 3.5	PASS
Largest single impurity	RP-HPLC — incomplete Fmoc removal (+222 Da)	0.89	% area	≤ 1.00	PASS
Identity — theoretical monoisotopic mass	calculated from molecular formula	4728.4871	Da	—	NOT TESTED
Identity — observed monoisotopic mass	LC-MS, unit resolution (single quadrupole)	4728.2781	Da	—	NOT TESTED
Mass accuracy	observed vs theoretical	-44.2	ppm	± 15	FAIL
Peptide content	not ordered on this submission	not determined	—	required to check label claim	NOT TESTED
Water content	Karl Fischer, coulometric, duplicate	7.08	%	≤ 8.0	PASS
Counter-ion (TFA)	anion-exchange ion chromatography	5.62	%	≤ 12.0	PASS
Residual solvent + inorganic residue	estimated — see /methods/residual-solvents-q3c/	0.84	%	—	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 lyophilised cake, intact	—	white to off-white intact cake	PASS
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	2.52	—	2.5 – 8.0	PASS
Retention time (observed)	RP-HPLC, 15 min gradient	11.19	min	11.18 ± 0.50 (normalised)	PASS
Peak asymmetry (10 % height)	Ph. Eur. 2.2.46	1.32	—	0.80 – 1.50	PASS
Plate count, main peak	N = 5.54 (t/w½)²	68,052	—	≥ 20,000	PASS
Resolution to nearest impurity	vs [D-Aib2]-diastereomer	0.63	—	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 68,052, and skew follows the reported asymmetry factor of 1.32. 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 0.89 % impurity against a 97.98 % 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	Retatrutide — main peak	11.19	4,762,132	97.98	—
2	incomplete Fmoc removal (+222 Da)	12.39	43,257	0.89	+222.068
3	oxidised Trp (+16 Da)	10.86	32,078	0.66	+15.995
4	des-Aib20 analogue	10.97	9,235	0.19	-85.053
5	[D-Aib2]-diastereomer	11.08	5,832	0.12	0.000
6	aspartimide (−18 Da)	11.54	4,860	0.10	-18.011
7	C18 diacid regioisomer	11.48	2,916	0.06	0.000
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 4728.4871 Da, computed from C221H342N46O68. 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 4728.2781 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 (%)
7+	676.5054	676.4756	-0.0298	8.6
6+	789.0885	789.0536	-0.0349	59.2
5+	946.7047	946.6629	-0.0418	100.0
4+	1183.1291	1183.0768	-0.0523	52.2
3+	1577.1696	1577.1000	-0.0696	7.9

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.

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)	98.25	97.98	divergence +0.42 pp vs batch median
Total impurities (% area)	1.75	2.02
Largest single impurity (% area)	0.60	0.89
Water (%)	5.3	7.08
Counter-ion (%)	not stated	5.62
Peptide content (%w/w)	not stated	not determined
Endotoxin (EU/mg)	not stated	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: Buyer-sourced
Evidentiary weight: Strongest available evidence in this index.
Chain of custody: Retail purchase → submitter (ambient, 6 d) → laboratory (courier, cold pack, 8 d) → assay.
Assay date: 21 Apr 2025
Submitted to the index: 03 May 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.
How much of the named compound is in the vial. Peptide content was not determined, so recovered mass cannot be calculated and the label claim cannot be checked.
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 3

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.

mass_defect03 May 2025

Mass-defect reasoning narrows this quickly. Very few plausible modifications of Retatrutide would produce a shift in the direction and magnitude observed, and the ones that would are all in the named-impurity table.

nmr_qnmr03 May 2025

Where mass spectrometry is unhelpful, quantitative NMR is orthogonal and does not care about ionisation. It is expensive and it is the correct next step on a record like this.

quad_unit03 May 2025

The purity, water and counter-ion figures on this record stand regardless of the mass question. Only the identity limb is affected, and the status field says exactly that.

Section 7

Related records

Same batch — lot GSP-2411-B2857 n=16

Report	Lot	Lab	Quarter	Purity %	Water %	Recovery %	Provenance	Flags	Result
AX-2025-019101	GSP-2411-B2857	Medutest	2025-Q2	98.36	7.25	—	Buyer-sourced	0	PASS
AX-2025-019102	GSP-2411-B2857	Janoshik	2025-Q2	98.03	7.22	98.7	Buyer-sourced	0	PASS
AX-2025-019103	GSP-2411-B2857	Janoshik	2025-Q2	97.39	7.16	105.7	Buyer-sourced	0	PASS
AX-2025-019104	GSP-2411-B2857	Janoshik	2025-Q2	97.96	7.23	—	Buyer-sourced	0	PASS
AX-2025-019105	GSP-2411-B2857	PeptideMeter	2025-Q2	97.71	7.59	94.6	Buyer-sourced	0	PASS
AX-2025-019106	GSP-2411-B2857	Janoshik	2025-Q2	97.58	7.19	104.1	Buyer-sourced	0	PASS
AX-2025-019107	GSP-2411-B2857	Medutest	2025-Q2	98.12	7.94	—	Buyer-sourced	1	FAIL
AX-2025-019108	GSP-2411-B2857	VendorInvestigate	2025-Q2	97.87	6.87	97.9	Buyer-sourced	0	PASS
AX-2025-019110	GSP-2411-B2857	Janoshik	2025-Q2	97.73	6.55	—	Buyer-sourced	0	PASS
AX-2025-019111	GSP-2411-B2857	PeptideMeter	2025-Q2	97.79	7.87	102.1	Buyer-sourced	0	PASS
AX-2025-019112	GSP-2411-B2857	Nordanalyt	2025-Q2	98.34	7.67	94.6	Buyer-sourced	0	PASS
AX-2025-019113	GSP-2411-B2857	Janoshik	2025-Q2	97.62	7.50	—	Buyer-sourced	0	PASS
AX-2025-019114	GSP-2411-B2857	Janoshik	2025-Q2	97.79	7.41	102.5	Buyer-sourced	0	PASS
AX-2025-019115	GSP-2411-B2857	PeptideMeter	2025-Q2	97.49	7.38	—	Buyer-sourced	0	PASS
AX-2025-019116	GSP-2411-B2857	Kestrel	2025-Q2	97.99	7.19	100.2	Buyer-sourced	0	PASS

Batch rollup and reproducibility assessment →

Cross-sections

Other recent Retatrutide records in the index.
Report	Supplier	Lot	Lab	Quarter	Purity %	Water %	Recovery %	Provenance	Result
AX-2026-042437	Homopeptide	HOMO-2605-V4718	Nordanalyt	2026-Q3	98.68	3.67	102.8	Buyer-sourced	PASS
AX-2026-043095	KP	KP-2607-H5774	Janoshik	2026-Q3	95.81	5.48	105.2	Buyer-sourced	FAIL
AX-2026-042282	TFC	TFC-2608-J1156	Janoshik	2026-Q3	98.54	4.27	—	Buyer-sourced	PASS
AX-2026-043094	KP	KP-2607-H5774	PeptideMeter	2026-Q3	96.32	6.40	—	Buyer-sourced	FAIL
AX-2026-042441	Homopeptide	HOMO-2605-V4718	Medutest	2026-Q3	98.93	4.22	—	Buyer-sourced	PASS
AX-2026-041427	QYB	QYB-2604-B4920	PeptideMeter	2026-Q3	97.93	2.45	101.7	Buyer-sourced	PASS
AX-2026-041786	ASY	ASY-{CAT}-2288	VendorInvestigate	2026-Q3	98.78	6.59	—	Buyer-sourced	PASS
AX-2026-041428	QYB	QYB-2604-B4920	Janoshik	2026-Q3	98.35	3.20	—	Laboratory-retained	PASS

Other recent GSP records in the index.
Report	Compound	Lot	Lab	Quarter	Purity %	Water %	Recovery %	Provenance	Flags	Result
AX-2026-041831	Survodutide	GSP-2603-E3156	Kestrel	2026-Q3	99.91	5.50	93.2	Buyer-sourced	0	PASS
AX-2026-041836	Survodutide	GSP-2603-E3156	Janoshik	2026-Q3	98.65	5.34	90.3	Buyer-sourced	0	PASS
AX-2026-041837	Survodutide	GSP-2603-E3156	Janoshik	2026-Q3	98.33	5.37	—	Buyer-sourced	0	PASS
AX-2026-041833	Survodutide	GSP-2603-E3156	Janoshik	2026-Q3	98.08	4.91	99.3	Buyer-sourced	0	PASS
AX-2026-041832	Survodutide	GSP-2603-E3156	VendorInvestigate	2026-Q3	98.01	5.14	99.5	Buyer-sourced	0	PASS
AX-2026-041835	Survodutide	GSP-2603-E3156	Nordanalyt	2026-Q3	98.34	5.74	89.0	Buyer-sourced	1	MARGINAL
AX-2026-041834	Survodutide	GSP-2603-E3156	VendorInvestigate	2026-Q3	97.92	5.95	—	Buyer-sourced	0	PASS
AX-2026-041838	Survodutide	GSP-2603-E3156	PeptideMeter	2026-Q3	98.30	5.01	102.4	Buyer-sourced	0	PASS