Compound Quality
Purity Is The Cheapest Test To Run. Here Are The Five Most Suppliers Skip.
A purity percentage is one test out of six. It is also the cheapest and most common one to publish. The other five are what actually tell you whether a batch is safe to trust.
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Almost every listing in this category prints a purity number. HPLC purity testing is fast, standardized, and cheap relative to the rest of the panel, which is exactly why it is the one everyone has.
It is also the least of the six checks that determine whether a batch is what it claims to be. Here are the other five, and what each one actually catches.
Catalyst runs all six on every batch.
Identity, purity, content, heavy metals, sterility and endotoxin, on one certificate, before anything ships.
Visit Catalyst Biolabs →1Identity (LC-MS)
Confirms the molecule itself by mass, not just how clean the sample is. A vial can score well on purity and never have this run at all.
Purity tells you it is clean. Identity tells you what it is.
2Quantitative content
Measures how many milligrams of actual peptide are in the vial, separate from the percentage on the label. A 99% pure vial can still under-deliver on total content.
A ratio is not an amount. Content is the amount.
3Heavy metals (ICP-MS)
Screens for lead, arsenic, cadmium and mercury, typically byproducts of manufacturing conditions rather than the peptide synthesis itself. This test has nothing to do with purity and will not show up on a purity-only certificate.
A high purity score says nothing about what else came along with the batch.
4Sterility
Cultured to confirm nothing is growing in the vial. This is a biological test, distinct from any chemical measurement, and it is run where applicable to the product form.
5Endotoxin (LAL)
A separate assay from sterility. Endotoxins are byproducts that can survive a process that already killed any live organisms, so a sterile result does not automatically mean an endotoxin-free one.
Sterile and endotoxin-free are two different findings, checked by two different tests.
Sample format, reflecting the fields Catalyst publishes on a Certificate of Analysis. Open a real, lot-specific certificate on Catalyst's own COA library.
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See all six checks on a real certificate.
Identity, purity, content, heavy metals, sterility and endotoxin, signed by an ISO/IEC 17025 accredited lab.
Open Catalyst Biolabs →6How to check any supplier in under a minute
- Count the tests, not just the purity number. Identity, content, heavy metals, sterility and endotoxin should each have their own line.
- Check the lab is named and independent. A result signed by the seller is not the same as one signed by a lab that does not sell the product.
- Match the lot number. A certificate for "this product" is not a certificate for the vial in your hand.
- Look for an accreditation, like ISO/IEC 17025. It is what makes the lab's own sign-off checkable in the first place.
| Test | Catalyst Biolabs | Typical supplier |
|---|---|---|
| Purity (HPLC) | Reported | Reported |
| Identity (LC-MS) | Reported | Often absent |
| Quantitative content | Reported | Usually absent |
| Heavy metals (ICP-MS) | Reported | Rarely reported |
| Sterility / Endotoxin | Reported | Rarely reported |
Read all six lines. Then decide.
Open any listing, read the full certificate for that exact lot, and count how many of the six checks actually appear.
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Comments
Went back through certificates from two other suppliers after reading this. Neither had a heavy metals line at all.
Same. I always assumed "third-party tested" meant all six. It usually just means purity.
Pulled the BPC-157 certificate before ordering. All six lines were there, lot number matched what arrived.
The sterile-versus-endotoxin-free distinction was new to me. Makes sense once you see it as two separate tests.
Checked the lab's accreditation number independently too. Matched what was on the certificate.
Ordering was straightforward, shipped same afternoon, certificate was already posted before it even arrived.