Understand the source comparison
How to Read P21 COA: Comparison of Analytical Methods
HPLC (Purity) Percentage of target peptide vs impurities ≥95% for research-grade Peptide identity, sequence correctness <92% purity, multiple secondary peaks >2% Mass Spectrometry Molecular weight matches theoretical structure ±1 Da from calculated MW Amino ac
No winner is assigned.
This page preserves a source comparison for education. It does not add a rating, recommendation or clinical judgment.
- HPLC (Purity)
- Percentage of target peptide vs impurities
- ≥95% for research-grade
- Peptide identity, sequence correctness
- <92% purity, multiple secondary peaks >2%
- Mass Spectrometry
- Molecular weight matches theoretical structure
- ±1 Da from calculated MW
- Amino acid sequence order, stereochemistry
- >±2 Da deviation, unexpected adducts
- Amino Acid Analysis
- Molar ratio of amino acids matches sequence
- ±10% of expected ratios
- D/L stereoisomers, post-translational modifications
- Missing expected residues, unexpected amino acids
- Endotoxin Testing
- Bacterial contamination level (for in vivo use)
- <1.0 EU/mg
- Non-bacterial contaminants, peptide purity
- >1.0 EU/mg for injectable protocols
- Professional Assessment
- All three tests must align. A peptide can pass HPLC purity but fail MS identity confirmation if the wrong compound was synthesized at high purity
- Use all three in combination, not individually
- None when all three are present and consistent
- Any single test failure invalidates the batch