Collect the manufacturer COA
Matched to the exact lot number. We check that the methods and results are complete.
Home/How We Verify
Dual verification
How we verify every compound lot
A manufacturer's COA is a useful starting point, but it's still the maker checking its own work. Double Check adds an independent lab test on the same compound lot. We pay for that test and publish the result, including the status while testing is in progress. If a lot fails, we pull it from sale.
Why two checks
One document is a claim. Two are evidence.
Some sellers pass along a manufacturer's COA without testing the lot themselves, or reuse one COA across several lots. A second test from an independent lab is designed to catch mislabeled, underfilled or degraded material.
- Same lot, not just the same productThe independent lab tests samples from the lot we sell, and the report carries that lot number.
- We pay the labThe manufacturer has no say in the independent test and doesn't pay for it.
- Both documents are publishedThe manufacturer COA and the independent report go into the public Double Check Reports archive.
Independent lab test
Samples from the same lot go to an independent analytical lab for purity, identity and net content. Our first compound lot is being tested by Kovera Labs.
Compare and publish
We publish both results for the lot. If the independent result doesn't confirm identity, purity or net content, the lot is pulled from sale and marked Rejected.
What we test
The three checks on every Double Check report
HPLC
Purity
The share of the sample that is the target compound, based on chromatographic peak area.
Mass spectrometry
Identity
Confirms that the observed mass matches the expected molecular mass, so you know the vial holds the right molecule.
Quantitative assay
Net content
How many milligrams are actually in the vial. High purity means little if the vial is underfilled.
Need an additional test for your QA file? Ask when you order.
How to read a COA
What to check before you trust a certificate
- Lot number matches the vialA COA without a lot number, or with a different one, tells you nothing about your vial.
- Who ran the testThe lab should be named. "In-house" means the seller tested its own product.
- Method statedPurity should name HPLC (with conditions), and identity should name MS. A bare "purity 99%" isn't a method.
- Net content, not just purityLook for measured mg per vial. Purity alone can hide an underfilled vial.
- Test dateRecent enough to reflect the material as it's being sold.
- VerifiableIndependent labs often give each report an ID or link you can check with them directly.
Certificate of Analysis
What each field should show
1Lot / batch numberMatches the vial
2Testing laboratoryNamed lab
3Purity · method% by HPLC
3Identity · methodConforms · MS
4Net contentMeasured mg
5Date testedRecent
6VerificationReport ID or link
Red flag: no lot numberA generic COA reused for every lot.
Red flag: purity onlyNo identity or content data at all.
Transparency
When a lot fails
If the independent check disagrees with the manufacturer, or doesn't confirm identity, purity or net content, we stop selling the lot. It is marked Rejected in the Double Check Reports archive with the reason, and we contact buyers who received it.
Need documents for your QA file?
Tell us what your purchasing or QA team needs to qualify VialTrust as a vendor.