Short answer: read a COA from top to bottom. Confirm who tested what and when, match the lot number to your vial, then compare each result with its specification. A result means little unless you know the limit it was measured against.
Step 1: Read the header
Find the laboratory name, the report or accession number, the client, and the received and reported dates. Note any verification code or QR code.
Step 2: Match the sample
Check the product name, labeled quantity and lot or batch number. The lot should match the label on the vial you have. Some reports also record cap color, appearance or a photo of the vial, which helps confirm that the sample is the same product.
Step 3: Read each test against its specification
Most COAs use a table with three columns: test, specification (the acceptance limit) and result.
- NLT means “not less than”. “Purity NLT 98%” means at least 98% is required.
- NMT means “not more than”. It is used for limits such as heavy metals or microbial counts.
- A “Pass” or a check mark means the result met that specification.
Step 4: Identity
Look for a method name such as LC-MS or MS and a statement that the measured mass matches the expected compound. Blends should confirm each component.
Step 5: Purity
Purity is usually an HPLC area percentage, for example 99.8%. Check the method (such as RP-HPLC with UV detection at 214 nm) and, if it is included, the chromatogram: a single dominant peak is what you expect to see.
Step 6: Content
Net content reports how much peptide was measured in the vial. It may be slightly above or below the label amount; the specification states the acceptable range.
Step 7: Safety screens
Endotoxin, microbial and heavy-metal results are usually reported as Pass/Fail or as a value below a limit.
Step 8: Read the fine print
Disclaimers often state that results apply only to the sample tested, and whether the laboratory sampled the batch itself or received a sample from the client. This matters when you judge how well a result represents a whole batch.
For a worked example, compare the GLOW batch record with its original PDF. You can also read our longer article, Guide to Understanding a Peptide COA the Right Way.
Related guides
- What Should a Peptide COA Contain?
- Identity Testing vs. Purity Testing
- Why Batch-Specific Testing Matters
- How to Verify Third-Party Lab Testing
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