Knowing what a COA should contain is half the job. The other half is proving the one in front of you is real, current, and actually tied to the vial you are about to buy. That's what this checklist is for.
If you need a refresher on what each test measures, start with What Every Test on a Peptide COA Actually Measures or the RUO Codes COA Verification Guide. Then come back here and run these seven steps before your next order, whether it's BPC-157, Tirzepatide or anything else in the Peptide Encyclopedia.
Step 1: Match the COA to the Product Lot
The first question is simple: does the COA belong to the item under review? Find the lot number or batch number on the product label, product page, or packaging and compare it directly with the lot number on the certificate. The compound name, stated quantity, and testing date should also make sense together.
A generic certificate labeled only “BPC-157” or “Tirzepatide,” with no lot identifier, cannot verify a particular batch. It may show that some material was tested at some point, but it does not establish that the current inventory came from that tested material. The same concern applies when a vendor displays one old COA across multiple product pages or leaves a certificate online long after the associated lot should have been exhausted.
Dates deserve context. A newer date is generally more useful, but a recent PDF is not enough if the underlying test was performed on a batch no longer sold. Look for a coherent chain: product lot, sample receipt or analysis date, report date, and the supplier's current stock. If any part of that chain is missing, treat the evidence as incomplete.
Step 2: Verify the Lab Is Real and Independent
Next, determine who performed the analysis. A meaningful COA identifies the testing laboratory by name and should provide enough information to distinguish it from the peptide seller. An independent lab is not merely a separate-looking logo. It is a laboratory with its own identity, contact information, report format, and analytical responsibility.
Supplier-issued quality sheets can be useful as internal records, but they are not equivalent to third-party testing. A vendor marking its own material as “99% pure” is making a claim. An independent lab report that names the tested sample, method, result, and analyst or authorized reviewer supplies evidence for evaluating that claim.
Check whether the report includes a laboratory report number, sample ID, instrument method, date of analysis, and approval or signature field. Not every legitimate lab uses the same layout, so the absence of one cosmetic feature does not automatically prove fraud. But several missing traceability fields should change the weight you give the document.
When the purchase is significant or the document raises questions, contact the lab through independently located contact details and ask whether it issued the report number for that vendor and lot. Do not rely solely on a phone number or email address printed on a questionable certificate. Some labs will confirm limited report details; others have privacy policies. Even a refusal to disclose details is more informative than assuming a PDF is genuine.
Labs the research community already recognizes include Janoshik Analytical, Freedom Diagnostics, ILS Laboratories, Vanguard Laboratory, Ethos Analytics, MDx BioAnalytical Laboratory and MZ Biolabs. Some, like Freedom Diagnostics, let you look up a report by its accession number. Use it. An unfamiliar lab name isn't automatically a problem, but a lab you can't find or contact is.
Step 3: Confirm Identity Before Purity
Purity is often the largest number on a peptide COA, and it is often the first number buyers notice. It should not be the first analytical question. A high purity percentage has limited value unless the material has first been identified as the compound the vendor says it is.
For many peptides, identity is commonly supported by mass spectrometry, such as LC-MS, which measures molecular mass. The reported mass should align with the expected molecular weight of the target peptide, accounting for the form being tested. Salt forms, acetate or trifluoroacetate counterions, hydration, and specific modifications can affect how a result is described. The report should make clear what material was expected and what was observed.
A chromatogram alone does not establish peptide identity. HPLC or UPLC can show that a sample has a major peak, but that peak must be tied to an identified compound through appropriate methods. A clean-looking chromatogram for an unknown substance is still a clean-looking chromatogram for an unknown substance.
For complex or modified compounds, identity confirmation may require more than a single molecular-mass match. Sequence confirmation, peptide mapping, or more detailed structural methods can provide stronger evidence, depending on the compound and the claim. The appropriate testing depth depends on the peptide, but identity should never be assumed from a product label.
Step 4: Read Purity Results in Context
HPLC or UPLC is commonly used to estimate peptide purity by measuring the relative area of chromatographic peaks. A result such as 99.1% purity can be meaningful, but only if the report identifies the method, sample, and result clearly. It should also be understood correctly.
Chromatographic purity is generally an area-percent measurement. It is not automatically a guarantee of biological activity, sterility, correct vial fill, or absence of every possible contaminant. It also may not capture impurities that the chosen method cannot detect or resolve. This is why “99% purity” should be treated as one testing category, not a universal quality verdict.
Review the chromatogram when available. Look for a labeled major peak, a stated purity calculation, retention time, and enough detail to show that the output belongs to the tested sample. A report that lists only a purity number without a method or supporting data is weaker than a complete analytical package.
Be cautious with implausibly uniform results. If every lot, every peptide, and every date reports exactly 99.9% purity, the consistency may reflect a template rather than real batch-specific testing. Real analytical results vary. Minor variation is normal, especially across different compounds and lots.
Step 5: Check Net Content Separately
Purity answers how much of the tested material is attributed to the target compound relative to measured components. Net content answers a different question: how much target peptide is actually present in the vial or sample.
This distinction matters. A vial may contain highly pure material while still containing less total peptide than its label claim. For a product labeled as 5 mg, meaningful documentation should support the stated content through an assay, quantitative method, or conformity testing that compares measured content with the label specification.
Do not assume that a vial's stated fill quantity is confirmed because the COA shows purity. A mass listed on a product page is a supplier claim unless the documentation ties a quantitative result to that lot. Likewise, a scale weight alone can be misleading if it includes container weight, moisture, salts, or excipients.
Step 6: Don't Confuse Purity With Safety Testing
Identity, purity, and net content form the baseline for evaluating whether a research peptide is what the supplier says it is. Other tests answer different questions and should not be folded into a single vague promise of “lab tested.”
Sterility testing addresses microbial growth under specified test conditions. Endotoxin testing evaluates bacterial endotoxin levels. Heavy metals testing looks for specific elemental contaminants. These are distinct analyses with separate methods, limits, and reports. A purity COA does not prove sterility, and a sterility result does not confirm peptide identity or assay.
The right level of documentation depends on the product claim and the research context. A supplier making sterile, low-endotoxin, or pharmaceutical-style conformity claims should provide corresponding lot-specific evidence. If those reports are absent, the claim should be treated as unverified, not filled in with assumptions.
Step 7: Scan for Documentation Red Flags
No single imperfection proves a certificate is fabricated, but patterns matter. The following signs warrant closer scrutiny:
A COA has no lot number, sample ID, report number, or test date.
The lab name cannot be independently located or the document provides no credible lab contact details.
Product name, quantity, lot number, or dates conflict with the item being sold.
The report provides a purity percentage but no identity method, chromatogram, or analytical detail.
The same certificate appears across unrelated lots, compounds, or extended periods of inventory.
The document contains obvious formatting errors, altered fields, mismatched fonts, or copied signatures.
A vendor does not need to publish every internal record to earn trust. It does need to provide enough current, lot-specific evidence for a buyer to verify the core claims. RUO Codes treats that threshold as a baseline for supplier evaluation because documentation is more useful than reassurance.
A COA is not a permission slip and it is not a substitute for regulatory, handling, or research safeguards. It is evidence to evaluate. The strongest purchasing decision is usually the least dramatic one: choose the supplier whose current lot documentation can be traced, interpreted, and independently checked without asking you to take its word for it.
Run the Checklist in Two Minutes
Don't want to do it by hand every time? Upload the COA to the RUO Codes COA Analyzer for an instant check against these same standards. Then compare vendors that pass in the vendor directory, where every approved vendor already meets the RUO Codes minimum testing standard. For the bigger picture on vetting a supplier, see How to Know If a Peptide Supplier Is Legit.
For research use only. This checklist evaluates documentation. It is not medical advice and does not replace your own legal and institutional obligations.