AssayIndex
Incretin analogues and co-agonists

Tirzepatide

LY3298176 · GIP/GLP-1 co-agonist · C225H348N48O68 · monoisotopic 4810.4103 Da. The index holds 576 assay reports on this compound across 96 batches from 20 suppliers.

576 reports96 batchesmedian 98.44 %index spec 97.0 %
Section 1

Analytical fingerprint

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

Tirzepatide is the hardest routine assay in the index. The molecule carries two Aib residues and a C20 diacid, and the resulting hydrophobicity puts it at 19.9 min on RG-2 with an unusually broad base — plate counts below 40,000 are common and the index rejects integration where the main peak's width at half height exceeds 0.35 min. Two impurities matter. Des-Aib2 at −85 Da is a synthesis artefact and sits 0.35 min early, frequently as an unresolved leading shoulder; rule AX-R12 exists largely because of it. [D-Aib13] is mass-identical and, on gradients shorter than 25 min, invisible. Reports from labs running a 15-min method routinely read 0.3–0.6 pp higher than RG-2 on the same lot, and the inter-lab page quantifies that offset. Base peak is [M+4H]4+ at m/z 1203.61.

Molecular formula
C225H348N48O68
Monoisotopic mass
4810.4103Da
Average mass
4813.45Da
Residues
39
Nominal retention (RG-2, 30 min)
19.86min
Retention window
0.45min
Counter-ion as usually shipped
TFA
Typical label claims
5 mg · 10 mg · 15 mg · 20 mg · 30 mg · 60 mg
Analytical difficulty (index scale)
1.40 — hard
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.

01339267840165355 Tirzepatide19.86 min · 98.44 % 19.5121.4823.84 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 Tirzepatide trace on the index reference method RG-2, constructed from this page's own numbers: the main peak carries the index median purity of 98.44 % area at the nominal retention time of 19.86 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 576 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 98.44% n=576
Interquartile range 1.23pp n=576
Minimum 95.92% n=576
Maximum 99.93% n=576
Pass rate vs spec 94.1% n=576
Median recovery vs claim 98.2% n=349
Median water 4.37% n=576
Median |mass error| 2.4ppm n=485
018365492.093.094.095.096.097.098.099.0100.092.00–92.25 %: 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=196.00–96.25 %: n=196.25–96.50 %: n=596.50–96.75 %: n=1396.75–97.00 %: n=1497.00–97.25 %: n=2297.25–97.50 %: n=2197.50–97.75 %: n=5497.75–98.00 %: n=4598.00–98.25 %: n=6398.25–98.50 %: n=5998.50–98.75 %: n=6098.75–99.00 %: n=5699.00–99.25 %: n=5699.25–99.50 %: n=4999.50–99.75 %: n=3099.75–100.00 %: n=27median 98.44 Purity (% area) Reports
Figure 2. Purity distribution across all 576 Tirzepatide records. Dashed line is this compound's median (98.44 %); the solid vertical is the index acceptance specification for the incretin analogues and co-agonists class (97.0 %). 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.

95.696.497.197.998.799.5100.3TFCTFC: Q1 97.98, median 98.35, Q3 98.75, n=65outlier 96.82n=65KPKP: Q1 97.55, median 98.16, Q3 98.85, n=56n=56HJHJ: Q1 98.11, median 98.40, Q3 98.81, n=48outlier 99.93n=48WWBWWB: Q1 98.66, median 99.14, Q3 99.50, n=47n=47QSCQSC: Q1 99.02, median 99.40, Q3 99.68, n=44n=44BCHBCH: Q1 97.13, median 97.42, Q3 97.84, n=38outlier 99.14n=38GGPepsGGPeps: Q1 97.93, median 98.40, Q3 99.16, n=36n=36SGNSGN: Q1 97.53, median 97.94, Q3 98.45, n=36n=36FGPFGP: Q1 97.70, median 98.37, Q3 99.08, n=29n=29JEEPJEEP: Q1 98.82, median 99.17, Q3 99.48, n=29n=29HomopeptideHomopeptide: Q1 98.32, median 98.67, Q3 98.99, n=28n=28WXTWXT: Q1 97.83, median 98.19, Q3 98.63, n=21outlier 99.93n=21ERPERP: Q1 98.06, median 98.64, Q3 99.11, n=20n=20CPCCPC: Q1 96.49, median 96.89, Q3 97.61, n=19n=19SWBSWB: Q1 97.75, median 98.63, Q3 99.27, n=16n=16SSASSA: Q1 97.53, median 97.71, Q3 98.06, n=15n=15MKMMKM: Q1 97.67, median 97.72, Q3 98.08, n=11n=11QYBQYB: Q1 99.00, median 99.23, Q3 99.48, n=9outlier 97.73n=9GL BiochemGL Biochem: Q1 97.37, median 97.93, Q3 98.57, n=7n=7QSTQST: Q1 98.36, median 98.46, Q3 98.55, n=2n=2 Purity (% area)
Figure 3. Tirzepatide 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
[D-Aib13]-diastereomer-0.19mass-identical85%0.172.72
des-Aib2 analogue-0.35-85.05382%0.182.10
Met(O) sulfoxide (+16 Da)-0.74+15.99576%0.102.19
C20 diacid mono-amide+1.62+0.98469%0.111.66
des-Gly deletion (−57 Da)-0.61-57.02167%0.131.63
trifluoroacetyl adduct (+96 Da)+0.93+95.98266%0.082.37
truncated (3-39)-1.48-222.11264%0.162.08
tirzepatide dimer+3.98+4810.41036%0.050.89

Degradation pathways

  • Met14 oxidation on exposure to peroxide-bearing excipients or air-saturated diluent
  • aspartimide formation at the Asp-Gly motif during synthesis, carried into the lot
  • slow deamidation of Asn in reconstituted material stored above 8 °C

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.

Tirzepatide's registrational data are the SURPASS diabetes programme (Lancet/NEJM, 2021–2022) and the SURMOUNT obesity programme (NEJM, 2022–2024). Research-grade material is not the clinical product and carries none of that evidence.

Section 7

Quarterly coverage

QuarterReportsMedian purityRange
2024-Q13098.7096.82–99.93
2024-Q23698.0796.55–99.78
2024-Q32398.2797.08–99.93
2024-Q42697.9196.65–99.93
2025-Q16899.2897.53–99.93
2025-Q26698.3996.55–99.69
2025-Q36698.1696.30–99.87
2025-Q46598.7696.41–99.93
2026-Q16698.3796.72–99.58
2026-Q29398.3996.86–99.93
2026-Q33798.3795.92–99.74

Quarter-by-quarter detail →

Section 8

Most recent records

The 25 most recent Tirzepatide records of 576.
ReportSupplierLotLabQuarterPurity %Water %Recovery %ProvenanceFlagsResult
AX-2026-043106KPKP-2608-D5921PeptideMeter2026-Q398.905.45105.4Supplier-supplied2MARGINAL
AX-2026-041742FGPFGP-2603-L9714Janoshik2026-Q399.372.43105.5Supplier-supplied1MARGINAL
AX-2026-043108KPKP-2608-D5921Janoshik2026-Q399.705.45—Supplier-supplied2MARGINAL
AX-2026-041741FGPFGP-2603-L9714PeptideMeter2026-Q398.622.57—Supplier-supplied1MARGINAL
AX-2026-043100KPKP-2608-D5921VendorInvestigate2026-Q398.275.3194.4Buyer-sourced2MARGINAL
AX-2026-043322CPCCPC-2607-L2552Janoshik2026-Q396.794.8896.1Supplier-supplied2FAIL
AX-2026-043111KPKP-2608-D5921PeptideMeter2026-Q399.715.15—Supplier-supplied2MARGINAL
AX-2026-043321CPCCPC-2607-L2552Kestrel2026-Q397.845.34—Supplier-supplied2MARGINAL
AX-2026-043105KPKP-2608-D5921Medutest2026-Q399.085.43—Supplier-supplied2MARGINAL
AX-2026-043112KPKP-2608-D5921Janoshik2026-Q398.855.68—Supplier-supplied2MARGINAL
AX-2026-043110KPKP-2608-D5921Janoshik2026-Q399.585.91104.9Supplier-supplied2MARGINAL
AX-2026-043323CPCCPC-2607-L2552Janoshik2026-Q397.195.4395.3Supplier-supplied3MARGINAL
AX-2026-043315CPCCPC-2607-L2552Janoshik2026-Q396.555.3496.5Supplier-supplied2FAIL
AX-2026-041961TFCTFC-2605-G5134Medutest2026-Q398.257.11—Supplier-supplied2MARGINAL
AX-2026-043319CPCCPC-2607-L2552Janoshik2026-Q396.325.2291.5Supplier-supplied2FAIL
AX-2026-043101KPKP-2608-D5921Janoshik2026-Q398.884.91101.3Supplier-supplied2MARGINAL
AX-2026-043325CPCCPC-2607-L2552Janoshik2026-Q397.184.3895.7Supplier-supplied2MARGINAL
AX-2026-041958TFCTFC-2605-G5134PeptideMeter2026-Q398.176.5493.0Supplier-supplied3FAIL
AX-2026-043317CPCCPC-2607-L2552Nordanalyt2026-Q396.435.42106.4Supplier-supplied2FAIL
AX-2026-043314CPCCPC-2607-L2552Medutest2026-Q396.925.2594.4Buyer-sourced3FAIL
AX-2026-041962TFCTFC-2605-G5134Medutest2026-Q398.616.36100.6Supplier-supplied2MARGINAL
AX-2026-041960TFCTFC-2605-G5134Janoshik2026-Q398.446.55—Supplier-supplied3MARGINAL
AX-2026-043316CPCCPC-2607-L2552Janoshik2026-Q396.145.00—Buyer-sourced2FAIL
AX-2026-043318CPCCPC-2607-L2552PeptideMeter2026-Q396.585.20—Supplier-supplied2FAIL
AX-2026-043103KPKP-2608-D5921Janoshik2026-Q398.915.86107.0Laboratory-retained2MARGINAL