Your COA Is Your Insurance Policy
A Certificate of Analysis (COA) is the single most important document accompanying a research peptide. It provides independent laboratory verification of identity, purity, and quality — the data your research integrity depends on. If your supplier can't provide a COA, or provides one without the sections below, reconsider that supplier immediately.
Key Takeaway
A valid COA must include: HPLC purity ≥98%, mass spectrometry identity confirmation (±1 Da), batch number, laboratory name, and chromatogram image. Missing any of these is a red flag.
Section 1: Product Information
Before diving into analytical data, verify the basics match your order:
- Peptide name and sequence — confirm it's the correct compound
- Molecular formula and weight — these should match published values
- Batch/lot number — a unique identifier for traceability
- Manufacturing date and expiry date
Section 2: HPLC Purity
The most important quality indicator. Look for:
- Purity percentage: Research-grade peptides should show ≥98% on RP-HPLC. Below 95% is questionable for research use.
- Chromatogram image: A graph showing peaks. Your peptide should be one dominant peak. Small satellite peaks (<2% combined area) are normal synthesis byproducts.
- Method details: Column type (typically C18), gradient conditions, detection wavelength (214nm standard).
Read our detailed guide on HPLC and MS methods for technical deep-dive.
Section 3: Mass Spectrometry
Confirms molecular identity. The observed mass must match the theoretical molecular weight within ±1 Dalton:
- Match: Confirms correct amino acid sequence
- Mismatch: Could indicate incorrect sequence, truncation, modifications, or wrong compound entirely
- Method: ESI-MS or MALDI-TOF (both are acceptable)
Section 4: Additional Tests
- Appearance: White to off-white lyophilized powder (most peptides). Blue-green powder for GHK-Cu.
- Endotoxin (LAL): Bacterial endotoxin levels should be <0.5 EU/mg.
- Bioburden: Microbial contamination count per USP <61> standards.
- Peptide Content: Net peptide content (typically 80-95% — the rest is counter-ions and moisture).
Red Flags
- No batch number (untraceable)
- No chromatogram image (may be fabricated)
- Purity below 95% without explanation
- No laboratory name or accreditation
- Molecular weight mismatch >2 Da
- COA template that looks identical across different products (generic/shared)
Every CertaPeptides order includes a full COA. See our testing protocol.