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How to Read a Certificate of Analysis: A Researcher's Guide to Verifying Peptide Purity

July 14, 2026 · 9 min read · Plato Peptides Research Desk

Why the COA Is the Foundation of Research-Grade Sourcing

A Certificate of Analysis (COA) is the single most important document accompanying any research peptide. It is the objective record of what a specific lot actually contains — not a marketing claim, but laboratory data. For researchers, the ability to read a COA critically is the difference between reproducible data and compromised experiments.

Not all COAs are equal. A legitimate document comes from an independent, accredited third-party laboratory and is specific to the lot you received. A generic or reused COA — one not tied to your batch number — provides little verification value.

HPLC Purity: The Percentage That Matters

High-Performance Liquid Chromatography (HPLC) is the standard method for assessing purity. On a COA, this appears as a percentage — for research-grade material, look for ≥98%, with many compounds exceeding 99%. The accompanying chromatogram should show a single dominant peak, indicating the target compound with minimal impurities.

Mass Spectrometry: Confirming Identity

Purity alone doesn't confirm identity. Mass spectrometry (MS) verifies that the compound is what it claims to be by measuring its molecular weight. A COA should list the expected molecular weight and the observed value. For example, tesamorelin should show a mass near 5,196 Da — not 3,358 Da (sermorelin) or 3,647 Da (CJC-1295). This is how mislabeled or substituted product is caught.

Additional Sections Worth Checking

Red Flags to Watch For

Be cautious of COAs with no batch number, no laboratory identification, missing mass spectrometry data, or purity claims unsupported by a visible chromatogram. A vendor that self-certifies its own purity without independent verification is, in effect, grading its own homework.

Every Plato Peptides order includes a COA from an independent third-party laboratory, delivered digitally with both HPLC purity and mass spectrometry confirmation.

⚠ Research Use Only — This article is for informational and educational purposes within a research context only. Nothing here constitutes medical advice or encouragement of human use of any compound. All Plato Peptides products are sold strictly for laboratory and research use.
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