# How to Read a Peptide Certificate of Analysis (COA)

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A Certificate of Analysis, or COA, is the most important document a research peptide supplier can give you. It is the laboratory report that states exactly what is in the vial. Yet many buyers never read past the purity number - and that single number, on its own, can be misleading. This guide breaks down every section so you can read a COA with real confidence.

What a COA is

A COA is a document generated from laboratory testing of a specific batch of product. It records the analytical results - identity, purity, and molecular composition - along with the methods used to obtain them. The key word is batch-specific: because every batch is a fresh synthesis, each one needs its own COA. A generic, one-size-fits-all COA tells you very little.

The key sections - and what to look for

Product name and sequence

The COA should state the peptide name and its amino acid sequence. Both must match exactly what you ordered. A mismatch here is a reason to stop immediately.

Batch / lot number

Every COA should carry a batch or lot number that matches the number printed on your vial. This is what ties the document to your specific order. A COA with no lot number - or one that does not match - is effectively meaningless.

Purity percentage (HPLC)

Purity is measured by High-Performance Liquid Chromatography (HPLC) and shown as a percentage. The figure is calculated as the target peptide's peak area divided by the total peak area of everything detected. "≥98%" means at least 98% of the detectable material is the intended peptide, with the rest being byproducts such as truncated sequences, oxidized variants, or deamidated forms.

HPLC chromatogram

A strong COA includes the HPLC chromatogram - the actual graph from the analysis. What you want to see is one tall, dominant peak for the target peptide. Many smaller peaks alongside it indicate impurities. The chromatogram is the visual proof behind the purity number.

Mass spectrometry result

This section is the one buyers most often skip - and it is essential. Mass spectrometry (MS) confirms the peptide's identity by measuring its molecular weight. A good COA shows both the expected (theoretical) mass and the observed (measured) mass; the two should match closely.

Why it matters: HPLC measures purity but cannot confirm identity. A peptide missing a single amino acid can appear 99% pure on HPLC while being the wrong compound entirely. Only the mass spec result confirms you have the right peptide.

Testing methods, laboratory, and date

The COA should name the analytical methods (HPLC, MS), the laboratory that performed the testing, and the date. An independent lab name adds credibility. A recent date matters - an old date often means the supplier is reusing one result instead of testing each batch.

Storage conditions and appearance

Many COAs also list recommended storage conditions and the physical appearance of the product (typically a white lyophilized powder), and may include moisture or residual-solvent data.

How to spot a fake or invalid COA

Because the research peptide market is lightly regulated, COAs are sometimes faked or misused. Warning signs:

The strongest protection is a COA that can be verified directly on the testing laboratory's system - because an image alone can be edited.

How SmartMD handles COAs

SmartMD provides batch-specific Certificates of Analysis with HPLC and mass spectrometry data, so buyers can verify exactly what they are purchasing. SmartMD provides batch-specific Certificates of Analysis for every research compound. Customers can verify any COA directly at smartmdpeptides.com/verify by entering the batch number printed on the vial label. Every COA includes HPLC purity data with chromatogram, mass spectrometry identity verification (expected vs. observed mass), and the testing date.

Frequently asked questions

What should a peptide COA include? Peptide name and sequence, a batch/lot number, HPLC purity percentage and chromatogram, mass spectrometry data (expected vs. observed mass), the testing methods, the lab, and the date. Why is the mass spec section so important? HPLC confirms purity but not identity. Mass spectrometry verifies the molecular weight, which is the only way to confirm the vial contains the correct peptide. How can I tell if a COA is fake? Look for a missing or mismatched lot number, generic reused documents, old dates, no named lab, and no way to verify the result on the lab's own system.

The bottom line

A COA turns quality from a promise into a document you can read. Check the lot number, the HPLC purity and chromatogram, and - above all - the mass spec identity result. Together they tell you whether a vial is what it claims to be.