How We Score COAs
Every Certificate of Analysis submitted to VialTalk is independently evaluated, then converted into a letter grade. That grade reflects two things at once: how strong the test results are, and how deep a testing panel the vendor chose to run.
Why a perfect basic COA still earns a B
The standard three-panel COA — purity, identity, and weight — structurally caps at a B, no matter how flawless the results are. Reaching an A requires at least one add-on test. This is intentional: a top grade should reflect not only clean results but the depth of testing a vendor was willing to commit to. A B is a genuinely respectable result for core testing — not a warning sign.
The core panel
These three components determine the baseline grade. Tap any test to expand.
PurityMost heavily weighted
Our most heavily weighted component. Purity measures what percentage of the product is the target compound. A strong purity result is the foundation of any valid COA — everything else builds on it.
IdentityMethod matters
Identity confirms the compound is what it claims to be. Crucially, not all identity methods are equal — the more definitive the method, the stronger the score.
- Mass Spectrometry (LC-MS/MS) and FTIR — The most rigorous methods. They confirm molecular identity directly and score highest.
- HPLC retention time alone — Less rigorous. It confirms a peak appears at the expected position, but does not definitively confirm the compound's molecular identity.
- PCR-based methods — Designed for DNA, not peptides, and carry the least weight in our model.
Weight / Net ContentTransparency earns full credit
Measures whether the vial actually contains what the label claims. Vendors who publish their tested weight against the labeled weight — on the COA itself, the product page, or the labeling — receive full marks for this component. Transparency here earns full credit.
Add-on tests
Optional tests that go beyond the core panel. Running one or more is what unlocks A, A+, and A++.
EndotoxinAdd-on
Screens for bacterial endotoxins that can cause inflammatory reactions. USP <85> and <161> are the accepted compendial standards. Running endotoxin testing signals a vendor is testing for safety beyond basic purity.
Heavy MetalsAdd-on
ICP-MS screens for toxic metal contamination that can arise from manufacturing processes or raw materials — a window into a vendor's process controls.
SterilityAdd-on
Confirms the product is free from viable microorganisms. USP <71> and microbial enumeration tests are the accepted methods.
Batch ConformityAdd-on
Validates multiple vials from the same manufacturing batch, not just the single submitted sample. Demonstrates manufacturing consistency across a production run.
Outside the score
One test we display but deliberately keep out of the grade.
Fentanyl Screen
Does not affect the gradeA fentanyl screen is not part of the scoring model. It appears in the panel count because it reflects a vendor's commitment to public safety — fentanyl contamination is a serious risk in research compounds, and vendors who run this screen are going above and beyond. We keep it outside the scoring framework because it tests for the absence of something dangerous rather than the quality of the product itself.
How the grades build
Each step up reflects more testing depth on top of strong results. We don't publish the specific score thresholds — the model is proprietary.
A solid core panel: purity, identity, and weight done right.
Strong core results plus at least one add-on safety or quality test.
An extended panel with outstanding results across multiple categories.
A full panel with outstanding results throughout.
Lab confidence grows over time
A vendor's results carry more weight as they document more COAs. A single submitted sample receives a modest confidence adjustment compared with a vendor that has a deep, consistent COA history — because consistent documentation over time is more meaningful than a single data point.
Third-party testing required
Every COA must come from a recognized third-party testing laboratory — in-house or self-testing is not accepted. Labs recognized as gold-standard by the peptide research community carry the most weight, and complete, well-documented COAs (product name, batch number, test date, method, and the attached document) let us evaluate every component fully.
What the public sees
Every approved COA is scored the same way regardless of vendor tier. What changes between tiers is how much of the scoring data is shown on the public vendor listing.
- Free tier: shows the product name, lab, purity, and test date. The COA Quality Grade is hidden, with an upgrade prompt in its place.
- Verified, Featured, Elite: full display — COA Quality Grade, weight accuracy, and the per-COA quality indicator.
Our scoring principles
New to COAs? Read about COA verification →
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