Purity Standards
Last updated: September 2026
Purity percentage tells you how much of the product is the actual peptide versus impurities. Here is what the numbers mean and why they matter for research.
What Purity Means
Purity is measured by HPLC (High-Performance Liquid Chromatography), which separates the components of a sample and measures what percentage is the target compound. A 99% purity rating means 99% of the sample mass is the peptide you ordered, and 1% is everything else (salts, solvents, related impurities, or truncated sequences).
Purity Tiers
99%+ (Research Grade)
The gold standard for research peptides. Minimal impurities, reliable for most protocols.
98% (Acceptable)
Common for many research peptides. Fine for most applications but verify the COA.
95-97% (Questionable)
Acceptable for some applications but expect more variability. Ask why purity is lower.
Below 95% (Avoid)
Too many impurities for reliable research. Not suitable for most protocols.
Common Impurities
- • Truncated sequences: incomplete peptide fragments from synthesis errors
- • Deleted sequences: peptides missing one or more amino acids
- • Residual solvents: chemicals left over from the synthesis process
- • Salts: counter-ions like TFA (trifluoroacetic acid) or acetate
- • Water: moisture absorbed by hygroscopic peptides
Why Purity Matters
Lower purity means you are dosing unknowns alongside your target peptide. Impurities can produce off-target effects, skew results, or introduce toxicity that confounds your data. For reproducible research, higher purity reduces variables and gives you confidence that observed effects come from the peptide itself.
Always cross-reference the purity percentage on the COA against the vendor's claims. If a vendor advertises 99% purity but the COA shows 96%, that is a mismatch worth questioning.
For laboratory research use only. Content is provided for research and educational purposes only and is not intended for human consumption, medical use, or diagnostic applications.