8 independent third-party assays of Semaglutide, covering 4 vendors.
Measured purity across those assays runs from 98.3% to 100.0%, median 99.6%. The spread is the point: it is variation between lots and between vendors, not a single number that describes the compound.
Assay dates span 2024-01-05 to 2025-11-19.
Manufacturer recorded on the certificates: Qingdao Sigma Chemical Co., Itd, Polaris Peptides.
Semaglutide carries an evidence grade of A on this site (FDA Approved). Semaglutide is an FDA-approved GLP-1 receptor agonist (MW ~4113.6 g/mol, molecular formula C187H291N45O59) with 94% sequence homology to human GLP-1. It is approved for type 2 diabetes (Ozempic), chronic weight management (Wegovy), and…
A certificate of analysis describes the lot that was submitted and nothing else. It is not a guarantee about a later batch, and purity is not identity — a sample can assay clean and still be the wrong compound, or the right compound at the wrong concentration. Vendors with no assay row below have not been tested here, which is not the same as having failed.
| Vendor | Assays | Median measured purity | Most recent |
|---|---|---|---|
| SEMA.BIO | 1 | 100.0% | 2024-01-05 |
| Polaris Peptides | 4 | 99.9% | 2024-08-16 |
| Reta-Peptide | 1 | 99.6% | 2025-11-19 |
| Qingdao Sigma Chemical QSC | 2 | 99.4% | 2024-11-04 |
Compound profile: Semaglutide — evidence, mechanism and safety.
Vendors assayed: SEMA.BIO, Polaris Peptides, Reta-Peptide, Qingdao Sigma Chemical QSC.