3 independent third-party assays of Glutathione 1500mg, covering 3 vendors.
Measured purity across those assays runs from 98.6% to 99.9%, median 99.9%. The spread is the point: it is variation between lots and between vendors, not a single number that describes the compound.
Assay dates span 2025-05-28 to 2026-02-26.
Manufacturer recorded on the certificate: Penguin Peptides.
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 |
|---|---|---|---|
| Penguin Peptides | 1 | 99.9% | 2025-07-28 |
| Qing Li Peptide | 1 | 99.9% | 2025-05-28 |
| UWA Elite Peptides | 1 | 98.6% | 2026-02-26 |
Vendors assayed: Penguin Peptides, Qing Li Peptide, UWA Elite Peptides.