The tests, in plain words
| Test | What it tells you | Question it answers |
|---|---|---|
| HPLC purity | The share of the detected signal that belongs to the target peptide, compared with related impurities. It does not count water or salts | How pure is the peptide itself? |
| Mass spectrometry (MS) | The molecular weight of what is in the vial, compared with the expected peptide | Is it the right compound? |
| Content or quantity | How many milligrams of peptide are actually in the vial | Is there as much as the label says? |
| Endotoxin | The level of bacterial endotoxins in the material | Is it free of this kind of contamination? |
| Sterility | Whether living microorganisms were detected in the samples tested | Did the tested samples grow anything? A pass covers the samples tested, not a guarantee for every vial |
| Heavy metals and residual solvents | Traces left from manufacturing | Is anything left over from production? |
The minimum for every batch
Every batch you sell should have, at a minimum, identity, purity and quantity from a named independent lab.
- Identity by mass spectrometry, so you know the vial holds the compound on the label.
- Purity by HPLC, with the percentage stated.
- Quantity per vial, because a pure vial with half the stated amount is still not what you sold.
Purity alone is not enough. A report that shows 99 percent purity says nothing about whether the compound is the right one or whether the vial holds the stated amount.
Tests buyers ask for
Wholesale buyers and more experienced researchers increasingly ask for endotoxin and sometimes sterility figures. Order them when your buyers ask, or when you want your reports to stand out against sellers who only show purity. Heavy metals and residual solvents come up less often, but some buyers ask for them on larger orders.
Reading the report
- Check the lab's name and that the report key opens the same report on the lab's own site.
- Check the lot number matches the batch you are selling.
- Check the test date, and any retest date the lab or supplier gives.
- Check the method is stated for each figure, not just a number.
Our guide on how buyers verify a peptide COA shows the quick version your buyers will use.
Budgeting testing
Prices vary by lab, by test and by how many samples you send, and they change, so get each lab's current price list. What matters for your margin is the cost per vial: divide the cost of testing a batch by the number of vials in it. Testing that looks expensive on a batch of twenty vials is a small line on a batch of several hundred.
Add the testing cost into your landed cost before you set a price. In the cost per milligram calculator, add it to the duties and fees box, and what it costs to start a research peptide business shows it in a full worked example.
Choosing a lab
Pick a lab that is independent of your supplier, names its methods, gives every report a key buyers can look up, and turns reports around fast enough for your reorder cycle. Our comparison of peptide testing labs covers the labs sellers use most.
Doing it in Purity
Purity reads what it can from the lab's report, such as purity, lab, test date and the report key, for you to check. Your release rules decide what a batch needs before it can be sold, such as a minimum purity, no failed identity check and a report in date. If you want identity confirmed on every batch, make that part of your own release check. You can mark a batch sent to the lab so nothing sits forgotten in quarantine. See it on the demo.
Common questions
- What tests should be on a peptide COA?
- At a minimum identity by mass spectrometry, purity by HPLC and quantity per vial, from a named independent lab. Buyers may also ask for endotoxin, sterility, heavy metals or residual solvents.
- What is the difference between HPLC and mass spec for peptides?
- HPLC measures how pure the peptide is compared with related impurities. Mass spectrometry checks the molecular weight to confirm it is the right compound. A good report has both.
- How much does peptide lab testing cost?
- It depends on the lab, the tests and how many samples you send, so get current price lists. For your margin, divide the cost of testing a batch by the vials in it to get a per-vial cost.