What Is a Certificate of Analysis?
A Certificate of Analysis (COA) is a document provided by a manufacturer or third-party lab that details the testing results for a specific batch of a peptide product. It's the single most important document for evaluating whether a peptide meets quality standards.
Key Sections of a COA
1. Product Identification
Look for the peptide name, batch/lot number, catalog number, and date of manufacture. Every COA should clearly identify which specific product and batch it refers to.
2. Purity by HPLC
High-Performance Liquid Chromatography (HPLC) is the gold standard for measuring peptide purity. Look for:
- Purity percentage: Research-grade peptides should be ≥95%, with premium products at ≥98-99%
- Method details: The specific HPLC method used (C18 column, gradient conditions)
- Chromatogram: A graph showing the separation of components — the main peak should be dominant
3. Mass Spectrometry (MS)
Mass spec confirms the molecular identity of the peptide. The observed molecular weight should match the theoretical molecular weight within acceptable tolerance (±1 Da for most peptides).
4. Appearance and Solubility
Physical characteristics like color (should be white to off-white for most peptides) and solubility in standard solvents.
5. Amino Acid Analysis
Confirms the amino acid composition matches the expected sequence.
6. Endotoxin Testing
Particularly important for injectable research applications. LAL (Limulus Amebocyte Lysate) testing should show endotoxin levels below acceptable limits.
Red Flags on a COA
- Missing batch/lot numbers
- No date or very old dates
- Purity below 95%
- No HPLC chromatogram included
- Generic or templated results that don't match the specific product
- No third-party lab identification
- Results that look identical across different batches
How to Verify a COA
- Check that the lab listed on the COA is a real, accredited testing facility
- Cross-reference the batch number with what's on your product label
- Contact the vendor and ask for the raw data or chromatogram files
- Compare results across multiple batches — legitimate testing shows natural variation