Why HPLC Certificates Matter When Buying Peptides: A Buyer's Guide
Not all peptides are what they claim to be. HPLC certificates are the only way to know what you're actually buying. Here's how to read them and what to look for.
The peptide market — particularly for research compounds — has a significant quality problem. Underdosed vials, incorrect peptides, contaminated products, and outright fakes exist at every price point. HPLC (High-Performance Liquid Chromatography) certification is the standard method for verifying what's actually in a vial. Any vendor unwilling to provide one should be avoided.
What Is HPLC?
HPLC is an analytical chemistry technique that separates the components of a mixture and measures their concentration. In peptide quality testing:
- A small sample of the peptide is dissolved and pushed through a column under high pressure
- Different compounds move through at different rates, creating separation
- A detector measures how much of each compound is present
- The result is a chromatogram showing peaks for each component and their percentage of the total
Reading a Certificate of Analysis
A legitimate CoA will show:
- Peptide name and molecular formula — confirms what compound was tested
- Purity percentage — the main peptide as a % of total sample. ≥99% is research grade.
- Chromatogram — the actual graphical output. The main peak should dominate with small or no impurity peaks.
- Retention time — confirms the correct compound (each peptide has a characteristic retention time)
- Batch number — traceable to a specific production run
- Test date — should be recent (within 6–12 months)
- Mass spectrometry (MS) confirmation — the gold standard, confirms molecular weight matches the target peptide
Purity Levels Explained
- ≥99% purity — research grade. Minimal impurities.
- ≥98% purity — acceptable for most research applications
- 95% purity — lower grade, may have detectable impurities
- Below 90% — reject. Significant unknown impurities.
Red Flags in Certificates
- No batch number (can't be verified as product-specific)
- Test date more than 12 months old
- No chromatogram — just a number (unverifiable claim)
- Purity of exactly 99.9% on every product (statistically improbable, likely fabricated)
- Cannot provide MS confirmation when requested
PeptideBazaar's Approach
Every product we sell comes with batch-specific HPLC and MS certificates from our manufacturer. We make these available on request with every order. If a vendor can't provide this documentation for a specific batch, move on.