Glow Peptides · Research Journal
Certificates of Analysis Explained: How to Read a COA and Why It Matters
Glow Peptides Research Team · 2026-06-10
For research use only. Not for human or veterinary use, diagnostic use, or in any therapeutic application.
What Is a Certificate of Analysis?
A Certificate of Analysis (COA) is a document issued by an analytical laboratory that verifies the identity, purity, and quality of a chemical compound. For research-grade peptides, the COA is the single most important quality document a supplier can provide.
Every lot of product shipped by Glow Peptides includes a COA. This article breaks down the key sections and explains what researchers should look for.
Key Sections of a Peptide COA
1. Product Identification
This section lists the peptide name, sequence (typically in single-letter amino acid code), molecular weight, lot number, and manufacturing date. Verify that the sequence matches your expected compound.
2. HPLC Purity
High-Performance Liquid Chromatography (HPLC) is the gold standard for peptide purity determination. Key values to review:
- Purity percentage: Research-grade peptides should be ≥ 98%. Values below 95% may introduce confounding variables in experimental results
- Method details: The column type (typically C18 reverse-phase), mobile phase composition, and gradient conditions should be documented
- Chromatogram: A well-resolved main peak with minimal satellite peaks indicates high purity. Broad or shouldered peaks suggest impurities or partial degradation
3. Mass Spectrometry (MS)
Mass spectrometry confirms the molecular identity of the peptide. The observed molecular weight should match the theoretical mass within ± 1 Da for ESI-MS or ± 0.1% for MALDI-TOF. Significant deviations suggest:
- Incomplete deprotection during synthesis
- Deletion sequences (missing one or more amino acids)
- Post-synthetic modifications (oxidation, deamidation)
4. Appearance and Solubility
The physical form (typically white to off-white lyophilized powder) and expected solubility in common solvents are noted. Unusual color or appearance may indicate degradation or contamination.
5. Endotoxin Testing
For peptides used in cell culture or in vivo research models, endotoxin levels are critical. The Limulus Amebocyte Lysate (LAL) test is the standard method:
- Acceptable levels: < 1 EU/mg for most research applications
- Elevated endotoxin can confound immunological assays, inflammatory marker studies, and cytotoxicity testing
6. Amino Acid Analysis (AAA)
Not always included, but available for critical applications. AAA confirms the amino acid composition and can reveal synthesis errors that MS alone might miss.
Red Flags to Watch For
- Missing chromatogram: A purity number without supporting HPLC data is unverifiable
- No lot number: Every batch should have unique traceability
- Old test dates: COA data should correspond to the manufacturing lot, not a generic reference
- Purity below specification: Even 1–2% impurity can significantly impact sensitive assays
Glow Peptides Quality Commitment
Every Glow Peptides product is accompanied by a lot-specific COA with full HPLC chromatogram, MS confirmation, and endotoxin data where applicable. COAs are available for download in your account dashboard and upon request.
For research use only. This content is educational and does not constitute medical or diagnostic advice.