What is a COA?
A Certificate of Analysis (COA) is a document from a laboratory that verifies the identity, purity, and quality of a peptide. Reputable vendors provide COAs for each batch they sell.
Key Elements to Look For
1. HPLC Purity
High-Performance Liquid Chromatography (HPLC) measures the purity of the peptide.
- 98%+ purity: Excellent, research-grade quality
- 95-98% purity: Good quality for most research
- Below 95%: May contain significant impurities
2. Mass Spectrometry (MS)
Mass spec confirms the peptide's molecular weight matches the expected value. Look for:
- Expected MW: The theoretical molecular weight of the peptide
- Observed MW: Should match expected within ±1 Da
3. Appearance
Should describe the physical form (typically "white to off-white lyophilized powder").
4. Batch/Lot Number
A unique identifier linking the COA to a specific production batch. This allows traceability.
Red Flags to Watch For
- Missing HPLC or MS data
- Generic COAs not specific to the batch
- No batch/lot number
- Purity significantly below 98%
- Large discrepancy between expected and observed molecular weight
Pro Tip: Request the COA before purchasing, or verify that the lot number on your product matches the COA provided. Quality vendors make COAs easily accessible.