AssayIndex
Acceptance specification

Incretin analogues and co-agonists

GLP-1, GIP and glucagon receptor agonists, including the lipidated long-acting analogues and the dual and triple co-agonists. 12 compounds in this class, 2,338 records.

12 compounds2,338 recordspurity spec 97.0 %observed median 98.65 %
Section 1

The specification

ParameterLimitWhere the limit came from
Purity by RP-HPLC≥ 97.0 % areaSet at the 1.7 th percentile of observed results for this class — low enough that ordinary material passes, high enough that a genuinely poor lot does not. Reviewed each quarter and last moved in 2025-Q1.
Water by Karl Fischer≤ 8.0 %Lyophilised peptides routinely carry 2–6 % residual water. The limit sits above the normal range and below the point at which water displaces enough cake mass to move the recovered-mass figure by more than the label tolerance.
Counter-ion≤ 12.0 %Derived from the stoichiometric maximum for a fully-protonated peptide of this class's typical basic-residue count, plus a margin. Above it, the salt is either non-stoichiometric or the cake contains free acid.
Bacterial endotoxin≤ 5.0 EU/mgAn index convention chosen so that the figure is comparable across records. It is not a pharmacopoeial limit: a real limit is dose-dependent and is computed per use from the K/M ratio. The endotoxin calculator does that calculation.
Mass accuracy± 15 ppmAchievable accuracy depends on mass. This class's limit reflects both the instrument capability and the mass differences that must be resolved within it — see mass-accuracy calibration.
Section 2

Compounds in this class

Per-compound thresholds override the class default where the chemistry requires it. Where a compound row differs from the class row above, the compound row wins.

CompoundMonoisotopic DaPurity specWaterCounter-ionppmRecordsObserved median
Semaglutide4111.052497.08.012.01576898.89
Tirzepatide4810.410397.08.012.01575098.55
Retatrutide4728.487196.58.012.01549298.37
Liraglutide3748.963197.58.012.0158899.00
Exenatide4183.937098.08.012.0154998.98
Cagrilintide3961.321896.58.012.0155498.69
Survodutide4764.512196.58.012.0157098.38
Mazdutide4912.640896.58.012.0152998.14
Pemvidutide4679.401496.08.012.015898.25
Glucagon3480.619498.08.012.0151599.20
GIP (1-42)4980.516397.08.012.0150n<3
Pramlintide3947.106497.58.012.0151599.10
Section 3

What actually fails, and how often

A specification nobody fails is not a specification. These are the failure rates the thresholds above produce on the records the index holds.

ParameterLimitRecords outsideRate
Purity≥ 97.0 % area351.50%
Water≤ 8.0 %80.34%
Counter-ion≤ 12.0 %20.09%
Endotoxin≤ 5.0 EU/mg80.34%
Mass accuracy± 15 ppm923.93%
08817626492.093.094.095.096.097.098.099.0100.092.00–92.25 %: 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=1296.75–97.00 %: n=2097.00–97.25 %: n=3997.25–97.50 %: n=6297.50–97.75 %: n=11397.75–98.00 %: n=19798.00–98.25 %: n=23798.25–98.50 %: n=29898.50–98.75 %: n=29298.75–99.00 %: n=31199.00–99.25 %: n=28399.25–99.50 %: n=21899.50–99.75 %: n=12699.75–100.00 %: n=123median 98.65 Purity (% area) Reports
Figure. Class-wide purity distribution with the acceptance specification drawn as a solid vertical and the observed median dashed. The area to the left of the solid line is the failure rate. A specification sitting deep in the left tail is doing its job; one sitting in the body of the distribution is measuring the population rather than screening it.