Understanding Certificates of Analysis: What Researchers Should Look For

Understanding Certificates of Analysis: What Researchers Should Look For

A Certificate of Analysis (COA) is the single most important quality document associated with a research-grade compound. It provides independently verified data about the identity, purity, and composition of a specific batch. For researchers, understanding how to read and evaluate a COA is essential to ensuring the integrity of experimental results.

What a COA Should Include

A complete COA for a research peptide typically includes:

**Compound Identity** — The compound name, amino acid sequence (for peptides), CAS registry number, molecular formula, and molecular weight. These fields confirm you have the correct substance.

**Purity Assessment** — Most commonly determined by High-Performance Liquid Chromatography (HPLC). Purity is expressed as a percentage, with research-grade materials typically specified at ≥98% or ≥99%. The HPLC method, column specifications, and chromatogram should be available.

**Mass Spectrometry (MS)** — Confirms molecular identity by measuring the mass-to-charge ratio. The observed molecular weight should match the theoretical value within acceptable tolerance.

**Batch and Lot Information** — The unique batch/lot number that ties the COA to the specific production run. This enables traceability.

**Testing Laboratory** — Whether testing was performed in-house or by an independent third-party laboratory. Third-party testing provides an additional layer of verification.

**Appearance and Physical Properties** — Visual description (e.g., white lyophilized powder), solubility data, and storage conditions.

Why Third-Party Testing Matters

In-house testing is standard practice, but independent third-party HPLC verification adds a layer of objectivity. When a supplier publishes COAs from accredited external laboratories, it demonstrates transparency and reduces the risk of confirmation bias in quality testing.

Red Flags

Researchers should be cautious of: - COAs that lack batch/lot numbers - Documents without a testing laboratory name - Purity claims without supporting chromatographic data - Generic or template-style COAs that appear identical across different batches - Suppliers who only provide COAs upon request rather than publishing them openly

At Pepterna

Every Pepterna batch undergoes third-party HPLC verification, and COAs are published directly on the product page — not behind a support ticket. We believe quality data should be accessible before purchase, not after.

All products are sold for research use only. Not for use in humans or animals.