Endotoxin testing for peptides: what the number on the certificate means
Published 5 October 2026 · Updated 5 October 2026
Short answer first.
Endotoxin is bacterial debris that stays behind after the bacteria are gone. The test for it is the LAL assay, and a useful result is a number in EU per vial. At Veritalys endotoxin is part of the plus endotoxin panel at €259 to €439 and the full panel at €439 to €629. At Janoshik it is a separate add-on at $180, about €155.
The rest of this guide explains what the number means and when it is worth paying for.
What endotoxin is
Endotoxin is a piece of the outer wall of certain bacteria (the gram negative kind). It is not alive. Kill the bacteria and the endotoxin stays. Filter the liquid and the bacteria are caught while the endotoxin passes through, because it is far smaller than the filter is built to stop. It also survives heat that kills everything that made it.
So sterile and endotoxin free are two different statements. A vial can grow nothing in a culture and still carry endotoxin from bacteria that lived and died somewhere upstream, usually in water or on equipment.
Why a number beats the word negative
A certificate that says "endotoxin: negative" tells you very little.
Negative against what limit? Endotoxin is measured on a continuous scale. Turning that scale into one word means somebody chose a cut off. If the cut off is not printed next to the word, you are reading their decision, not your measurement. Two sellers can print the same word for very different samples.
A number does not have that problem. EU stands for endotoxin unit. EU per vial is the amount in the container you were sent, which is the thing you wanted to know. Every Veritalys report gives endotoxin as a number in EU per vial, and when a specification applies, it is printed in the same row.
What the two services publish
| Veritalys | Janoshik | |
|---|---|---|
| How endotoxin is sold | inside a panel with identity, content and purity, €259 to €439 | separate add-on, $180 (about €155) |
| Method | quantitative LAL | LAL assay |
| Reported as | EU per vial | EU per vial for powder, EU per ml for liquid, standard reporting range 1 to 1000 EU per vial |
| Microbiology alongside it | aerobic count, yeast and mould, E. coli and Salmonella, in the full panel at €439 to €629 | sterility test (aerobic count plus yeast and mould), reported pass or fail, $290 |
Janoshik figures are from their own product pages, last checked 4 October 2026. Their pages also say a separate vial is preferred for endotoxin, and that they do not offer endotoxin analysis on oils, raw powders, tablets or capsules.
A worked example with BPC-157: identity, content and purity plus endotoxin costs €279 at Veritalys against about €340 at Janoshik for the same two tests. The full panel is €449 against about €589, and ours adds E. coli and Salmonella.
When endotoxin is worth paying for
- When the material will go into a biological system in your work. Endotoxin triggers a response that can look like a result and is not one.
- When the vial was filled somewhere you cannot see. Endotoxin comes from water and equipment, not from the molecule, so it is a question about the filling line, not the chemistry.
- When you sell the product. Buyers ask for purity first. Cleanliness is the number that protects you when one of them asks a harder question.
- When the certificate you were shown said negative and printed no limit.
When it is the wrong purchase
If your question is "is this the right compound, and is the vial full", identity, content and purity answers it from €169. Endotoxin answers a different question. Decide which question you are asking before you pick a panel. The guide Which peptide test do you need? walks through the choice.
What the number cannot tell you
It is about one vial. Contamination is not spread evenly across a production run, so a clean result is evidence about the container tested, not the whole batch.
It is not a purity result either. A vial can be clean and still hold the wrong molecule, or the right molecule at two thirds of the labelled amount. Those answers come from separate tests, explained in Purity is not content.
Questions people ask
What is endotoxin testing?
A measurement of bacterial endotoxin in a sample, done with the LAL assay and reported as a quantity in EU per vial rather than as a pass or fail word.
What does EU per vial mean on a COA?
EU means endotoxin unit, a measure of endotoxin activity. Per vial means the total amount in the container that was tested.
Does sterile mean endotoxin free?
No. Endotoxin is not alive, survives the treatments that kill bacteria, and passes through the filters that stop them. A vial can pass a microbiology test and still carry it.
How much does endotoxin testing cost?
At Veritalys endotoxin comes inside a panel: €259 to €439 with identity, content and purity, or €439 to €629 in the full panel with microbiology. Janoshik sells it as an add-on at $180, from their product page checked 4 October 2026.
Is negative a valid endotoxin result?
Only if the limit behind the word is printed beside it. Without the limit you are reading a judgement, not a measurement.
Can every sample be tested for endotoxin?
Freeze-dried powder and liquids can. Janoshik states it does not test oils, raw powders, tablets or capsules for endotoxin. If your sample is unusual, email us before you post it.
Veritalys prices come from the live price list. Janoshik prices are from janoshik.com product pages, last checked 4 October 2026, with $1 taken as €0.86.
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