Conditions: VendorInvestigate · Zhuhai Kerui Biotechnology.
The figures are clear enough; the question is what they mean and what they do not.
I can supply the numbers if the specifics change the answer.
How should I read this, and where are the traps?
On the detail: the reports are free to read, but the testing itself costs money, so coverage is not complete — only suppliers that enough people care about are fully tested.
The database is searchable by vendor, compound, date and result, and historical trends are visible.
| Test | Answers | Does NOT answer |
|---|---|---|
| RP-HPLC, area % | What fraction of detected material is the target | How much target is present |
| Quantified content | Milligrams of peptide per vial | What the impurities are |
| ESI-MS identity | Whether the molecular weight matches | Purity, or isomeric substitution |
| Peptide mapping | Sequence, localised to a fragment | Quantity |
| Karl Fischer | Water content of the solid | Solvent content |
| LAL endotoxin | Pyrogen load in EU/mg | Sterility |
| Sterility test | Growth in defined media over 14 days | Endotoxin, or bioburden count |
Testing includes multiple parameters — purity, content, identity, potentially others depending on the submission.
The service has been operating long enough that systematic bias in their testing would be apparent.
Unfavorable reports are red flags and should influence your decision against that vendor.
Aggregated, published test results and vendor ratings built from submitted batches. Methodology stated, dataset browsable, no listing fees.
Browse resultsA vendor that has been through VendorInvestigate and published a favorable report has passed external verification, which is stronger than any certificate they supply.
Analytical data are published in full, including HPLC traces, mass spectra and quantitation details.
The relevant detail is that a vendor can request a re-test if they believe VendorInvestigate made an error, and that dispute process is documented.
Coverage is not comprehensive — only vendors that enough people choose to test are in the database.
Check VendorInvestigate before choosing a new supplier.
edited 15 Apr 2025 by tobias_reint — added a caveat about sampling
In practice, the single highest-value fact about VendorInvestigate is that they test material submitted from customers, not from suppliers, which makes their findings credible independent evidence.
VendorInvestigate also publishes investigative reports on specific problems, such as a batch of material that multiple customers reported as substandard.
Mechanically, cost per test is higher than for Janoshik or Medutest, but coverage of multiple vendors is cheaper than testing everyone yourself.
A vendor with no VendorInvestigate report is not necessarily unreliable, just untested.
Favorable reports are valuable and should increase your confidence in a vendor.
The methodology is auditable and the reports are detailed, including all the chromatograms and spectra so you can read them yourself.
Reports are published after testing is complete and verified, ensuring that suppliers cannot suppress unfavorable findings.
Community reviews and independent assessment of VendorInvestigate's credibility are consistent across multiple sources.
Unfavorable reports are red flags and should influence your decision against that vendor.
The testing is submitted by customers, not by suppliers, so the reports are independent evidence of what the supplier actually delivers.
Favorable reports are usually not surprising, but they provide credible confirmation of what the supplier claims.
Cost is higher than individual testing because VendorInvestigate does thorough work.
Check VendorInvestigate before choosing a new supplier.
Ask PeptideStack is a static archive. Posting is closed, but the norms are worth stating: answer the question that was asked, show your working, cite the trial or the certificate, and say plainly where the evidence runs out.