How We Verify Purity
PeptideLists applies rigorous scientific verification methods to ensure accuracy of purity claims and lab quality standards.
Certificate of Analysis (COA) Verification
Every vendor's purity claims are verified through:
- ✓Analysis of HPLC (High-Performance Liquid Chromatography) data
- ✓Verification of third-party laboratory credentials and accreditation
- ✓Cross-reference with international testing standards (USP, BP, Ph. Eur.)
- ✓Confirmation of batch-specific results (not generic claims)
- ✓Comparison against historical COA data for consistency
HPLC & Chromatography Standards
High-Performance Liquid Chromatography is the gold standard for peptide purity testing:
Separation & Detection
HPLC separates peptide components and quantifies purity percentages with high accuracy
Wavelength Analysis
UV detection at specific wavelengths (typically 214nm or 280nm) identifies peptide presence
Peak Identification
Main peptide peak must represent ≥95% of total area for research-grade quality
Impurity Detection
Minor peaks identify residual solvents, salts, and other byproducts
Laboratory Accreditation Verification
Third-party testing labs must meet international standards:
- ✓ISO 17025 accreditation (International Organization for Standardization)
- ✓GLP (Good Laboratory Practices) compliance
- ✓Current calibration of analytical equipment
- ✓Trained and certified analytical chemists
- ✓Quality control protocols and documentation
PeptideLists Purity Classification
We classify vendors based on verified purity standards:
≥99% Purity
Tier 1Highest standards. Consistent COA documentation. Multiple independent verifications.
98-99% Purity
Tier 2High-grade compounds. Strong COA history. Industry reputation established.
95-98% Purity
Tier 3Research-grade standards. COA documentation available. Baseline for listing.
Below 95%
UnlistedNot recommended. May indicate quality control issues or incomplete purification.
Red Flags We Look For
We flag vendors for further investigation if:
- ⚠COA lacks specific HPLC data or peak percentages
- ⚠Testing lab is not independently accredited
- ⚠COA dates are outdated or unavailable
- ⚠Purity claims exceed 99.9% (unrealistic for peptides)
- ⚠No batch-specific information provided
- ⚠Third-party testing shows discrepancies vs. claimed purity
We Recommend Independent Verification
While PeptideLists conducts rigorous vendor verification, we strongly recommend:
- •Requesting updated COAs directly from vendors
- •Independent third-party testing of received products
- •Comparing multiple COAs from the same vendor over time
- •Consulting with qualified laboratory professionals