How to Read a COA

What Is a Certificate of Analysis?

A Certificate of Analysis (COA) is a quality control document that records the results of analytical testing performed on a specific batch of a compound. In the research peptide context, a COA should confirm compound identity and purity for the exact production lot you are purchasing.

A COA is not a general quality statement or a marketing document. It is a test record tied to a specific lot number.

Key Fields in a COA

Lot Number

The most important field. The lot number on the COA must match the lot number printed on the label of the vial you received. If these do not match, the COA does not document what is in your vial.

Test Date

The date the compound was tested. A COA with a test date significantly earlier than your order may reflect outdated testing on a different batch. Fresh lot-specific testing is preferable.

Test Method

Describes how testing was performed. Look for HPLC (High-Performance Liquid Chromatography) for purity quantification, and MS (Mass Spectrometry) for identity confirmation. A COA listing only HPLC confirms purity but not identity. Both methods together provide complete verification.

Purity (%)

Expressed as a percentage of the target compound relative to all detected components. A result of 99.2% means 99.2% of the detected chromatographic signal corresponds to the target molecule. Impurities account for the remaining 0.8%.

For research purposes, 98%+ is generally considered research-grade. 99%+ is the standard for high-purity applications. Anything below 95% warrants caution.

Appearance

A description of the physical form of the compound — typically "white lyophilized powder" for peptides. This provides a basic visual reference for what you should expect upon receipt.

Testing Laboratory

Identifies who performed the testing. Independent third-party laboratory testing is more reliable than manufacturer self-reporting. Ask suppliers whether their COAs reflect external or internal testing.

Release Status

A Pass/Fail or Released/Rejected determination. A compound released against a specification confirms the lot met defined quality criteria at the time of testing.

Red Flags in COA Documentation

• Lot number mismatch. The COA lot number does not match the vial. The documentation does not apply to your compound.
• No test method listed. If a COA does not state how testing was performed, the purity figure is not independently verifiable.
• No independent lab identified. Manufacturer-only testing without third-party verification provides limited assurance.
• Suspiciously round purity numbers. Results like "99.0%" or "100%" that never vary across lots may indicate estimated rather than measured values.
• Generic or undated documents. A COA without a test date may be a template, not an actual test record.
• No HPLC chromatogram data reference. A complete HPLC COA typically references chromatogram data that can be reviewed for peak shape and baseline quality.

How OPSEK Labs Handles Documentation

Every order from OPSEK Labs includes a lot-specific COA that corresponds to the exact batch shipped. Testing is performed by an independent third-party laboratory using HPLC for purity quantification and mass spectrometry for identity confirmation.

Compound specifications including molecular weight, sequence, appearance, and storage conditions are published on each product page. Documentation questions can be directed to support@opseklabs.com.

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