COA & testing
Why Peptide Purity Claims Differ Between Suppliers
2026-05-02 · 5 min read
Purity is a measurement, and measurements come with methods. Comparing headline percentages across suppliers without comparing methods is not a comparison.
Method differences
Gradient, column, and detection wavelength all shift the reported number. A COA that omits the method omits the context.
What is counted as an impurity
Related peptides, counter-ions, and residual water may or may not be included depending on how the report is written. Ask what the denominator is.
The practical test
Buy one kit, assay it yourself or read the third-party trace, then scale. A one-kit minimum makes that test cheap.
Ordering, minimums, and pricing
Every SKU is priced per vial and sold in sealed ten-vial kits with a one-kit minimum. Volume tiers: 1 kit at list, 2 kits at 5% off, 3 kits at 7% off, 5 kits at 12% off, and 10 kits at 20% off. Domestic orders received by 2PM PT dispatch the same business day, and freight is free above $2,500.
All compounds are sold as chemical reagents for laboratory research use only — not for human or veterinary use.
Frequently asked
- What is the minimum order?
- One ten-vial kit of any in-stock SKU. Mix compounds freely to reach a volume tier.
- Do orders include a certificate of analysis?
- Yes — lot-specific, with third-party HPLC purity and mass-spec identity.