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RESEARCH GUIDES9 min readJune 08, 2026

How to read a peptide Certificate of Analysis (COA)

A practical UK guide to reading a research-peptide Certificate of Analysis. What HPLC, mass spectrometry, and purity readings actually tell you, and how to verify the authenticity of a laboratory report.

VB

Written By

Velvet Bronze Scientific Advisory

How to read a peptide Certificate of Analysis (COA)

Why Verification Matters in Peptide Sourcing

In the research peptide industry, a Certificate of Analysis (COA) is the primary document that validates compound identity and chemical purity. Without a verifiable COA from an independent analytical laboratory, any statement about a peptide's purity is merely a marketing claim.

Unfortunately, the duplication and alteration of analytical reports are common practices. As a researcher, understanding how to read, interpret, and directly verify a COA is essential to maintaining laboratory safety and experimental integrity.

HPLC: Understanding the Chromatogram

High-Performance Liquid Chromatography (HPLC) is the gold standard for verifying peptide purity. The output of an HPLC test is a chromatogram, which shows a graph of ultraviolet absorption over time.

When analyzing an HPLC chromatogram, look for the following metrics:

1. Retention Time: The time it takes for the target compound to travel through the chromatography column. The major peak represents the target peptide.

2. Peak Area Percentage: Purity is calculated by dividing the area of the main peak by the sum of all peak areas. For example, a purity of 99.72% means that 99.72% of the detected UV absorption at the target wavelength corresponds to a single compound.

3. Impurity Peaks: Any minor peaks on the graph represent impurities or synthesis byproducts. A premium compound should show flat baselines with negligible secondary peaks.

Advisory Note

"A genuine HPLC chromatogram should show a sharp, symmetrical main peak. Wide, asymmetrical peaks or multiple secondary peaks indicate degradation or incomplete synthesis."

Mass Spectrometry: Confirming Identity

While HPLC measures purity, it does not confirm the identity of the molecule. A sample could yield a 99% pure HPLC reading for the wrong compound. To solve this, laboratories use Mass Spectrometry (MS).

MS determines the molecular weight of the compound. The resulting spectrum shows a major peak at the mass-to-charge ratio (m/z) corresponding to the target peptide's molecular weight. For instance, if you are testing BPC-157, the molecular mass peak must align precisely with its theoretical weight of 1419.5 Da. A mismatch indicates that the vial contains a different substance entirely.

Checking for Independent Verification Red Flags

When evaluating a COA, verify these security features to confirm its authenticity:

1. Direct Verification URL: Reputable testing companies (like Janoshik Analytical) provide a unique URL or QR code on the PDF. You can visit the laboratory's database and check that the report matches their records exactly.

2. Report Date and Batch Reference: Ensure the analysis date is recent and aligns with the batch lot number. A COA from three years ago does not represent the purity of a batch manufactured last month.

3. Clear Laboratory Contact: The document must list the laboratory name, contact details, testing methods, and analyst signature. Anonymous or heavily redacted COAs are a major red flag.

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