Headline findings
of peptides show purity discrepancies vs. supplier COA claims
average gap between supplier-claimed and measured purity
of supplier COAs exactly match independent lab results
of samples contain heavy metals above USP safety limits
Methodology
Sample size: 1,400+ peptide samples submitted for independent third-party testing between January 2024 and February 2026.
Methods: Reversed-phase HPLC for purity (Agilent 1260 Infinity, Waters Alliance), ESI-MS / LC-MS/MS for identity, ICP-MS for heavy metals (USP <232>/<233>), GC-MS for residual solvents (ICH Q3C), LAL assay for endotoxin (USP <85>).
Discrepancy definition: A sample is counted as discrepant when measured purity differs from the supplier-provided COA value by more than 1.0 percentage point.
Supplier blinding: Most samples submitted with supplier source disclosed by client; results reported without supplier identification in this aggregate dataset.
License: Statistics on this page may be cited and reproduced under CC-BY 4.0 with attribution to ACS Peptide Testing Labs (acslabtest.com).
Discrepancy rate by peptide class
Percentage of samples in each class where measured purity disagreed with the supplier COA by more than 1 percentage point.
Discrepancy rate by supplier source
Where the peptide was purchased meaningfully predicts COA accuracy.
Most common impurity types
When peptides fail purity expectations, these are the dominant culprits.
Cite this dataset
Free to use in articles, research, and protocols with attribution. Suggested citation:
ACS Peptide Testing Labs (2026). Peptide Testing Statistics 2026: 1,400+ Sample Independent Lab Study. Retrieved from https://acslabtest.com/peptide-testing-statisticsLooking for the underlying methodology articles? Read the COA accuracy study or the discrepancy breakdown.