AssayIndex
Incretin analogues and co-agonists

Semaglutide

NN9535 · GLP-1 analogue (Aib8, C18 diacid) · C187H291N45O59 · monoisotopic 4111.0524 Da. The index holds 926 assay reports on this compound across 123 batches from 19 suppliers.

926 reports123 batchesmedian 98.87 %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.

Semaglutide is the index's most-submitted compound and its behaviour is well characterised here. On RG-2 it elutes as a single sharp peak at 18.4 min with an asymmetry factor typically 1.05–1.18; the C18 diacid side chain drives strong C18 retention, so any material eluting before 17.5 min is almost always a linker-truncated species rather than the target. The diagnostic impurity is des-AEEA semaglutide at −145 Da, which co-elutes 0.8 min early and is present in essentially every synthetic lot at 0.1–0.6 % area. The [D-Aib8] diastereomer is mass-identical and resolves only partially at 40 °C; lots reporting 99.5 %+ on a short isocratic method have almost certainly integrated the diastereomer into the main peak, and the index treats such submissions as method-limited rather than high purity. Charge-state envelope is dominated by [M+4H]4+ at m/z 1028.77 and [M+5H]5+ at 823.22.

Molecular formula
C187H291N45O59
Monoisotopic mass
4111.0524Da
Average mass
4113.58Da
Residues
31
Nominal retention (RG-2, 30 min)
18.42min
Retention window
0.45min
Counter-ion as usually shipped
TFA
Typical label claims
2 mg · 3 mg · 5 mg · 10 mg · 15 mg
Analytical difficulty (index scale)
1.25 — moderate
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.

01449289943485798 Semaglutide18.42 min · 98.87 % 17.6019.7822.13 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 Semaglutide trace on the index reference method RG-2, constructed from this page's own numbers: the main peak carries the index median purity of 98.87 % area at the nominal retention time of 18.42 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 926 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 98.87% n=926
Interquartile range 1.09pp n=926
Minimum 96.37% n=926
Maximum 99.93% n=926
Pass rate vs spec 99.2% n=926
Median recovery vs claim 98.4% n=520
Median water 4.56% n=926
Median |mass error| 2.7ppm n=782
0377411192.093.094.095.096.097.098.099.0100.092.00–92.25 %: 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=096.00–96.25 %: n=096.25–96.50 %: n=196.50–96.75 %: n=096.75–97.00 %: n=697.00–97.25 %: n=1797.25–97.50 %: n=3197.50–97.75 %: n=4297.75–98.00 %: n=5998.00–98.25 %: n=7698.25–98.50 %: n=7798.50–98.75 %: n=8698.75–99.00 %: n=12699.00–99.25 %: n=13099.25–99.50 %: n=11599.50–99.75 %: n=7499.75–100.00 %: n=86median 98.87 Purity (% area) Reports
Figure 2. Purity distribution across all 926 Semaglutide records. Dashed line is this compound's median (98.87 %); 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.

96.196.897.598.298.899.5100.2HomopeptideHomopeptide: Q1 98.94, median 99.20, Q3 99.61, n=121outlier 97.76n=121WWBWWB: Q1 98.91, median 99.08, Q3 99.48, n=111outlier 97.67outlier 97.95outlier 97.99n=111QSCQSC: Q1 98.94, median 99.23, Q3 99.43, n=67outlier 97.41outlier 98.13n=67TFCTFC: Q1 98.42, median 98.78, Q3 99.16, n=57n=57BCHBCH: Q1 97.77, median 98.16, Q3 98.77, n=56n=56WXTWXT: Q1 97.53, median 98.02, Q3 98.75, n=52n=52GGPepsGGPeps: Q1 98.00, median 98.25, Q3 98.78, n=50n=50SWBSWB: Q1 98.22, median 98.66, Q3 99.32, n=47n=47KPKP: Q1 97.72, median 98.45, Q3 99.27, n=41n=41ERPERP: Q1 98.24, median 98.77, Q3 99.25, n=40n=40JEEPJEEP: Q1 98.87, median 99.13, Q3 99.56, n=39n=39MKMMKM: Q1 98.29, median 98.61, Q3 99.03, n=39n=39HJHJ: Q1 98.55, median 99.00, Q3 99.45, n=37n=37SSASSA: Q1 97.72, median 98.23, Q3 98.77, n=36n=36GL BiochemGL Biochem: Q1 97.44, median 98.10, Q3 98.93, n=32n=32SGNSGN: Q1 97.85, median 98.09, Q3 98.57, n=32outlier 99.79outlier 99.91n=32CPCCPC: Q1 97.63, median 97.88, Q3 98.51, n=25n=25FGPFGP: Q1 99.35, median 99.59, Q3 99.77, n=22outlier 98.65n=22QYBQYB: Q1 98.99, median 99.14, Q3 99.49, n=22n=22 Purity (% area)
Figure 3. Semaglutide 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
des-AEEA semaglutide (−145 Da)-0.82-145.07480%0.182.23
[D-Aib8]-diastereomer-0.24mass-identical80%0.182.11
C18 diacid mono-ester+1.36+14.01675%0.101.70
deamidated (Asn→Asp, +1 Da)-0.51+0.98472%0.102.18
des-His1 truncate (−137 Da)-1.14-137.05969%0.071.85
Met(O) sulfoxide (+16 Da)-0.68+15.99556%0.071.92
tBu-protected residual (+56 Da)+2.05+56.06347%0.061.29
semaglutide dimer+3.71+4111.05230%0.071.08

Degradation pathways

  • side-chain amide hydrolysis at the AEEA-AEEA linker under alkaline stress
  • Asn26 deamidation accelerating above pH 8
  • fibrillation on agitation of reconstituted material held above 25 °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.

Cardiovascular outcome data for semaglutide 2.4 mg come from SELECT (NEJM, 2023); weight-management efficacy from the STEP programme (NEJM, 2021) and renal outcomes from FLOW (NEJM, 2024). None of that applies to research-grade material of unknown provenance, and the index takes no position on use.

Section 7

Quarterly coverage

QuarterReportsMedian purityRange
2024-Q12498.8696.82–99.93
2024-Q26898.5697.09–99.93
2024-Q38098.7397.29–99.93
2024-Q47098.8397.52–99.93
2025-Q110298.7797.08–99.93
2025-Q24599.0297.17–99.93
2025-Q312598.7796.92–99.93
2025-Q415298.8796.97–99.93
2026-Q17998.9697.07–99.93
2026-Q29699.2097.36–99.93
2026-Q38599.0896.37–99.93

Quarter-by-quarter detail →

Section 8

Most recent records

The 25 most recent Semaglutide records of 926.
ReportSupplierLotLabQuarterPurity %Water %Recovery %ProvenanceFlagsResult
AX-2026-041334WWBWWB-2606-N3192Janoshik2026-Q398.835.04—Supplier-supplied1MARGINAL
AX-2026-041932TFCTFC-2604-X4301Janoshik2026-Q398.884.31—Supplier-supplied0PASS
AX-2026-042347HJHJ-2608-C3931VendorInvestigate2026-Q398.803.41100.2Buyer-sourced1MARGINAL
AX-2026-041886JEEPJEEP-2607-X3911Nordanalyt2026-Q399.194.0396.4Supplier-supplied2MARGINAL
AX-2026-041337WWBWWB-2606-N3192Nordanalyt2026-Q398.964.81—Supplier-supplied1MARGINAL
AX-2026-042172HomopeptideHOMO-2604-X8921Janoshik2026-Q399.645.1691.9Supplier-supplied1MARGINAL
AX-2026-041767FGPFGP-2602-M1508PeptideMeter2026-Q398.652.54—Supplier-supplied2FAIL
AX-2026-041882JEEPJEEP-2607-X3911Nordanalyt2026-Q399.174.52—Supplier-supplied1MARGINAL
AX-2026-041335WWBWWB-2606-N3192Janoshik2026-Q399.554.55100.5Supplier-supplied1MARGINAL
AX-2026-041328WWBWWB-2606-N3192Janoshik2026-Q399.484.59—Supplier-supplied1MARGINAL
AX-2026-042398SWBSWB-2602-X5278Nordanalyt2026-Q399.084.48—Supplier-supplied1MARGINAL
AX-2026-041333WWBWWB-2606-N3192Janoshik2026-Q398.804.5190.6Laboratory-retained1MARGINAL
AX-2026-043406WXTWXT-2604-C4728Janoshik2026-Q397.244.65—Supplier-supplied1MARGINAL
AX-2026-042399SWBSWB-2602-X5278Janoshik2026-Q398.563.82—Supplier-supplied1MARGINAL
AX-2026-042388SWBSWB-2602-X5278Nordanalyt2026-Q398.093.90—Supplier-supplied1MARGINAL
AX-2026-041936TFCTFC-2604-X4301PeptideMeter2026-Q398.624.30—Buyer-sourced1MARGINAL
AX-2026-041772FGPFGP-2602-M1508Janoshik2026-Q399.793.03107.5Supplier-supplied0PASS
AX-2026-041770FGPFGP-2602-M1508VendorInvestigate2026-Q399.331.4890.3Buyer-sourced1MARGINAL
AX-2026-041769FGPFGP-2602-M1508Janoshik2026-Q399.132.5592.9Supplier-supplied1MARGINAL
AX-2026-042167HomopeptideHOMO-2604-X8921Janoshik2026-Q399.575.06104.9Supplier-supplied2MARGINAL
AX-2026-042348HJHJ-2608-C3931Nordanalyt2026-Q399.524.19—Supplier-supplied1MARGINAL
AX-2026-042178HomopeptideHOMO-2604-X8921Janoshik2026-Q399.385.21101.3Supplier-supplied2MARGINAL
AX-2026-043401WXTWXT-2604-C4728Medutest2026-Q397.704.7891.5Supplier-supplied1MARGINAL
AX-2026-041768FGPFGP-2602-M1508Janoshik2026-Q398.852.2090.3Supplier-supplied1MARGINAL
AX-2026-042392SWBSWB-2602-X5278Janoshik2026-Q398.663.47—Supplier-supplied1MARGINAL