The short answer: you can't test a peptide for purity at home. Purity, identity and contamination are measured in a lab, with instruments, on a sealed vial you mail in.
What you can do is know which test answers which question. A "99% pure" result answers one question out of about six, and it's usually not the one that puts people in the hospital.
Here's what each test actually measures, how people use independent labs and public result databases, and where all of it runs out.
Last checked October 21, 2026. Prices and policies are as the labs list them today and change often. None of the labs named here are endorsed, and nothing here is medical advice.
Where I get mine: the vendors I use, and how I vetted them.
What does each peptide lab test actually tell you?
Each test answers one narrow question. None of them answers "is this safe to inject?"
Test | What it answers | What it can't tell you |
|---|---|---|
HPLC purity | What share of the material it detects is the main peptide | What the peptide is, how many mg are in the vial, or anything about bacteria or toxins |
Mass spectrometry (MS) | Whether the molecule has the right molecular weight | How pure it is, how much is there, or whether it's sterile |
Quantity / net peptide content | How many mg of actual peptide are in the vial | Whether the rest is harmless salt and water or something worse |
Endotoxin (LAL) | How much bacterial endotoxin is present | Whether live bacteria or other fever-causing contaminants are present |
Sterility | Whether microbes grew from the vials tested | Endotoxin levels, or whether the next vial is sterile too |
Heavy metals | Whether specific metals (usually arsenic, cadmium, lead, mercury) are detected | Anything about the peptide itself, or metals that weren't on the panel |
The rest of this post is the detail behind each row.
What does HPLC purity mean?
It's a percentage of peaks on a chart, not a percentage of your vial. HPLC separates the contents of a sample, and a UV detector draws a peak for each thing it sees. Bachem, one of the largest peptide manufacturers, explains that "the area of the main peak in relation to the total area of all peaks reflects the peptide purity" (Bachem).
So "99% pure" means 99% of the peaks the detector saw belong to the main peptide. Bachem notes that water and counterions like TFA "are not measured by the same methods used to determine the purity" (Bachem). Neither are bacteria or endotoxin.
HPLC on its own also doesn't prove the main peak is the right peptide. It proves there's one dominant thing in the vial.
What does mass spec add?
Identity. Mass spectrometry weighs the molecule. BPC-157 has a molecular weight of about 1,419.5 (Janoshik's BPC-157 listing). If the main signal matches, that's strong evidence you have BPC-157 and not something else.
This matters more than people think. In the largest dataset of grey-market peptide tests so far, 156 vials didn't contain the peptide on the label at all (BHN on the Mendias and Awan preprint). A purity number alone wouldn't catch that if the wrong peptide was also clean.
If a test report shows a purity percentage but doesn't say how identity was confirmed, that's the first question to ask. The COA guide covers what to look for on the page itself.
Why can a 99% pure vial still be underdosed?
Because purity and quantity are different measurements. A freeze-dried peptide is never 100% peptide by weight. Bachem says the peptide content of the solid "may range from 70 to 90%," with the rest made up of counterions and moisture (Bachem).
Then there's the fill. A vial labeled 10 mg can hold 7 mg of very pure peptide. The Mendias and Awan analysis scored samples on measured amount as well as purity, and between 41.6% and 71.1% failed basic quality criteria depending on how strict the standard was (Mendias and Awan, Preprints.org, Apr 2026).
The reverse happens too. A 2024 study that bought semaglutide from flagged online sellers found every vial had 29% to 39% more semaglutide than the label said (Ashraf et al., J Med Internet Res, 2024).
How do you test peptides for endotoxins?
With an LAL assay, in a lab. Endotoxins are bacterial toxins that, in Finnrick's words, "can trigger fever or adverse reactions" (Finnrick). FDA says it has accepted the LAL test for endotoxins in place of the rabbit pyrogen test "for more than 30 years" (FDA, March 2026).
Three things to know:
Purity doesn't predict it. In the Mendias and Awan dataset, 15% of samples had measurable endotoxin, a result a purity number can't show you (Mendias and Awan, Preprints.org, Apr 2026).
It's usually an add-on. Finnrick's own methodology says endotoxin testing isn't required and "most lab panels do not include it" (Finnrick).
It only catches endotoxin. FDA's guidance tells manufacturers to separately assess the risk of "non-endotoxin pyrogens," other fever-causing contaminants the LAL test isn't designed to catch (FDA, March 2026).
The semaglutide study is a good example of why this sits apart from purity. Endotoxin was detected in all three vials, from 2.16 to 8.95 EU/mg, even though no live microbes grew from any of them (Ashraf et al., J Med Internet Res, 2024).
Is a pure peptide sterile?
No. Purity is chemistry. Sterility is microbiology. They're tested by different methods, and one says nothing about the other.
A sterility test grows whatever is in the sample and reports pass or fail. Janoshik, for example, describes its version as a cultivation test for bacteria, yeast and mold that needs two unopened vials and returns "Pass or Fail" (Janoshik).
A pass means those vials grew nothing. It doesn't mean the vial in your fridge is sterile, and it can't tell you anything about what happens once you start putting needles through the stopper. That part is covered in how long mixed peptides last.
Can you test peptides at home?
Not for purity, identity or endotoxin. I couldn't find any consumer kit validated to measure any of those for peptides.
The colorimetric peptide assays that do exist are lab reagents that measure total peptide concentration in a solution, not purity. Thermo Fisher's own page for its peptide assay says it's "not recommended for synthetic peptides," because the amino acid makeup changes the color reading (Thermo Fisher). A color change tells you peptide is present. It can't tell you which one, how pure, or what else is in there.
Even harm-reduction drug-checking services, which test street drugs every day, say they can't do this. Switzerland's Saferparty answered the question of whether it can analyze peptides with "The answer is no," and noted that a result "often says little about how safe a product actually is" (Saferparty, Aug 12, 2026).
What you can do at home:
Look at it. Cloudiness, particles or color change are real warning signs. Clear doesn't mean fine.
Verify the report, not just read it. Labs that publish verification tools let you check that a COA is real and matches the product (more below).
Check the batch. A report is only useful if its batch or lot number matches what's printed on your vial.
How does Janoshik testing work?
Janoshik is a commercial lab that tests peptides, steroids and other compounds for whoever sends a sample. It describes itself as "an independent testing laboratory" (Janoshik). Its About page doesn't mention any accreditation.
From its own listings, as of today:
Basic peptide test. BPC-157 analysis is $215, by HPLC, and reports mg per vial and purity. It needs one whole unopened vial (Janoshik).
Add-ons. Endotoxin by LAL assay ($180 standalone), sterility ($290), heavy metals for arsenic, cadmium, lead and mercury by X-ray fluorescence ($145 standalone), plus options like fentanyl screening and LC-MS contamination screening (Janoshik).
Verification. Every report can be checked on its Verify page with a task number and unique key, or by the QR code on the report (Janoshik). This is what people mean by "Janoshik verify."
Public results. A public database lists reports that customers chose to publish, with a note that Janoshik doesn't endorse anyone listed (Janoshik public results).
The catch with the public database: many listings are "tested by" the seller. The vendor picked the vial, named the sample and paid for the test. Verification proves Janoshik issued the report. It doesn't prove that vial came from the same batch you bought.
How does Finnrick testing work?
Finnrick is a testing platform for US buyers that sends peptide samples to partner labs and publishes the results with vendor ratings. Its homepage listed 12,441 published test results today (Finnrick).
From its own pages:
Where samples come from. "Samples come from public submissions and Finnrick purchases," and vendor-submitted samples are labeled (Finnrick).
What's tested. Identity, purity and quantity by HPLC on every sample. Endotoxins, heavy metals, residual solvents and sterility are add-ons (Finnrick).
Price. Free community testing for eligible samples (identity, purity, quantity, about 4 weeks, US residents only). A $249 standard tier adds endotoxins. Custom orders start at $69 (Finnrick).
Ratings. Weighted pass rates, with newer tests counted more. It says it doesn't accept payment to change rankings (Finnrick).
Finnrick's data is what the Mendias and Awan preprint analyzed: 6,441 samples across 14 peptides, with 41.6% to 71.1% failing basic quality criteria depending on how strict the standard was (Mendias and Awan, 2026). The full breakdown is in what's actually in the vial.
Same caveat as Janoshik. These are third parties. You can read their methods, but you can't audit their labs, their sample handling or their incentives from the outside. The preprint's own authors concluded that consumer testing improves transparency but "captures only a small fraction of the safety profile" (Mendias and Awan, 2026).
What are the limits of third-party peptide testing?
The big ones:
One vial is not a batch. A test describes the vial that was tested. Whether the rest of the batch matches is an assumption.
The sender picks the vial. A vendor-submitted sample can be the best vial they have.
Purity is not sterility. A 99.9% HPLC result says nothing about bacteria or endotoxin.
Most panels skip contamination. Endotoxin, sterility and metals cost extra, so most published reports don't include them.
A real report can be the wrong report. A verified COA for a different batch, or a different seller's product, still verifies.
Labs aren't regulators. None of this is the testing an FDA-approved product goes through. That gap is what research-grade vs pharmaceutical-grade is about.
The short version
You can't test peptide purity at home. Color kits measure presence, not purity.
HPLC says how pure. Mass spec says what it is. Quantity says how much. You need all three.
Endotoxin and sterility are separate tests, and most published reports don't include them.
Janoshik and Finnrick publish real lab data, but a report describes one vial, often picked by the seller.
In the biggest dataset so far, at least 41.6% of grey-market samples failed basic quality criteria.
Next step: see the vendors I use and how they score on testing, reviews and support. Code BHN40 takes 40% off.
If you've sent a vial off for testing, reply and tell me what you tested for and what came back. Especially if the purity looked great and something else didn't.