The case in front of me: VendorInvestigator · Sangon Biotech (Shanghai).
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?
The short answer is that VendorInvestigator is expensive because they do thorough testing, but the cost is paid once per supplier rather than per lot.
Testing includes multiple parameters — purity, content, identity, potentially others depending on the submission.
| 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 |
Worth being precise here: analytical data are published in full, including HPLC traces, mass spectra and quantitation details.
Community reviews and independent assessment of VendorInvestigator's credibility are consistent across multiple sources.
Coverage is not comprehensive — only vendors that enough people choose to test are in the database.
Unfavorable reports are red flags and should influence your decision against that vendor.
Analytical standards and reagents with traceable certificates. Every quantitative result you read inherits the accuracy of the standard behind it.
Shop standardsVendorInvestigator publishes content assay data, purity data, identity confirmation and analytical traces, giving you the full picture of what the supplier is shipping.
Reports are published after testing is complete and verified, ensuring that suppliers cannot suppress unfavorable findings.
Stated carefully, vendorInvestigate also maintains a risk registry flagging vendors with multiple unfavorable reports or reports of customer problems.
Cost is higher than individual testing because VendorInvestigator does thorough work.
Check VendorInvestigator before choosing a new supplier.
The part that matters: the single highest-value fact about VendorInvestigator is that they test material submitted from customers, not from suppliers, which makes their findings credible independent evidence.
Cost per test is higher than for Janoshik or Medu Laboratories, but coverage of multiple vendors is cheaper than testing everyone yourself.
Concretely, vendorInvestigate also publishes investigative reports on specific problems, such as a batch of material that multiple customers reported as substandard.
VendorInvestigator reports are submitted through formal channels and involve independent verification before publishing.
Favorable reports are valuable and should increase your confidence in a vendor.
edited 16 Jul 2026 by tare_weight — reworded for clarity after a comment
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.
Reports include the dates of testing and the lot numbers of the tested material, tying the result to specific material.
A vendor with no VendorInvestigator report is not necessarily unreliable, just untested.
If you only pay for one test, pay for quantified content. Purity is the number everyone quotes and content is the number that changes what you do.
A vendor that has been through VendorInvestigator and published a favorable report has passed external verification, which is stronger than any certificate they supply.
The database is searchable by vendor, compound, date and result, and historical trends are visible.
The service has been operating long enough that systematic bias in their testing would be apparent.
In practice: ask for the chromatogram, check the method section, check the lot number against the vial, and set your accept threshold before you see the result rather than after.
Ask Peptide 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.