How to test peptides: get your vials lab tested in 9 steps, from choosing tests to verifying the report

How to test peptides: the nine steps

Peptide testing works by post: you send sealed vials to a lab, and the lab sends back a report. Steps 1, 4 and 5 decide whether the result is usable: the right tests, the right vials, and vials the lab can match to your form.

Step	What you do	Detail
1. Choose the tests	Match each test to a question	Full peptide panel
2. Choose a lab	Read a sample report first	12 checks
3. Get a quote	Give the product, label claim, lot, vials and tests	Peptide testing cost
4. Choose the vials	Sealed, at random, extra vials for safety tests	How many vials
5. Number the vials, fill in the form	A sample number on each vial, the form in the box	Custody form
6. Pack and ship	Upright, bagged, padded, tracked	How to send peptides
7. Chain of custody	Check the lab’s receipt record and photo	Step 7 below
8. Read the results	Each number with its method, unit and basis	How to read a COA
9. Verify the report	Open it on the lab’s own site	Verify a COA

The steps are the same for one vial of your own, a group test or a brand’s batch. The three routes are compared at the end.

How to test peptides yourself: what a home kit cannot do

People who test their own peptides want three answers: is it the right peptide, how pure is it, and how many mg are in the vial. No home kit we found gives any of them for a synthetic peptide. Identity needs a mass spectrometer. Purity needs HPLC. The mg figure needs a reference standard of known content.

Our September 2026 market research found home kits for hGH and steroids, but none that identify GLP-1 peptides, BPC-157 or GHK-Cu, and none for endotoxin. Details: peptide test kits.

At home you can check the seal, check that the lot matches the seller’s report, and compare the powder with the seller’s photos. Past that, testing your own peptides means sending your own sealed vial to a lab, alone or with a group.

Step 1: choose the tests (how peptides are tested in a lab)

Start with the question you need answered. Each test answers one.

Your question	Test	How the lab measures it	Reported as
Is it the peptide on the label?	Identity	LC-MS: measured mass matched to expected mass	Both masses, error in ppm
Which GLP-1 is in this vial?	Blind GLP-1 identification	LC-MS against a list of candidate peptides	The peptide found, or a mix
What share is the target peptide?	Purity	HPLC with UV detection	% of UV peak area
How much peptide is in the vial?	Content per vial	Quantitative HPLC against a reference standard	mg per vial and % of label
Is there endotoxin?	Endotoxin	LAL test	EU per mg and per vial
Can microbes grow from it?	Sterility	USP <71>, at least 14 days of incubation	Growth or no growth, units tested
What else is in the powder?	Counter-ion, water, residual solvents	Chromatography (TFA, acetate); Karl Fischer; gas chromatography (solvents)	% of the powder; named solvents
Do vials in a batch match?	Vial-to-vial consistency	Content measured on 3 or more vials	Mean, range and relative standard deviation

For most buyers the core is identity, purity and content, usually from one vial. Purity and content are separate numbers: a vial can be 99% pure and hold 6 mg where the label says 10. ICH Q6A, the international guideline on specifications, says retention time alone is not specific, so ask for identity by mass. Add endotoxin and sterility when contamination is the question. They are two different tests, and each needs its own sealed vial. The test pages explain each method.

Step 2: choose a lab by its reports

Read a sample report before you send anything. Four checks catch most weak reports:

• Identity shown by mass, with the expected and observed values printed.
• Purity and mg as two separate numbers, with the chromatogram behind them.
• Endotoxin as a number in EU, and sterility named as the 14-day USP <71> test.
• A way to open the report on the lab’s own site with an ID and a key.

If a lab claims ISO/IEC 17025 accreditation, check that your test is in its scope document. The full list: how to choose a peptide testing lab.

Then check two things. Many sellers honour refund claims only with results from labs they name; see which lab results vendors accept. And labs measure differently. In Peptide Critic’s published comparison of one retatrutide batch, five labs and the seller’s own report gave between 10.18 and 12.80 mg, a spread of about 26%. To retest later, use the same lab, or read why labs disagree.

Step 3: get a quote and the lab’s sample paperwork

Ask first and pack second. A parcel that arrives without the lab’s paperwork can wait unlogged. Chromate gives its shipping address only after payment. Freedom Diagnostics’ web form ends with a barcode packing slip for the box. Krause Analytical’s chain of custody form has a row per sample for the name, the label claim in mg, the batch or lot, and the test.

For the quote, have ready the product name exactly as labelled, the label claim in mg, the lot, the number of vials and the tests from step 1. A useful quote states what each test costs, how many vials each needs, and which event starts the lab’s clock: receipt, log-in or payment.

Step 4: choose the vials

• Sealed, as sold. Freedom Diagnostics asks for a crimped, unopened vial. An opened vial can pick up microbes and endotoxin in handling, which spoils those tests.
• At random. Take vials from different kits or boxes. A vial the seller picked tells you less.
• One lot per sample. Two lots are two samples.
• Enough vials. Identity, purity and content usually share one vial. Endotoxin and sterility each need their own unopened vials. Vial-to-vial consistency needs one vial per result, so three or more.
• A spare. Keep one sealed vial of the same lot for a dispute or a second lab.

Counts by test and by lab: how many vials for testing.

Step 5: number the vials and fill in the custody form

Write a sample number on each vial or its bag. Keep the product label on, because it links the vial to the lot. If you do not want the analyst to see the mg claim, cover only the claim.

Fill in a custody form by hand. Per sample: the sample number, the product name as labelled, the label claim (or “withheld”), the lot and the number of vials. Per parcel: seals intact or not, who packed it, the date, the carrier and the tracking number. Copy the lot exactly as printed, and photograph each vial and cap before you seal the box. Our printable sample custody form has these fields.

Step 6: pack and ship with tracking

Stand the vials upright in a sealed bag, cushion them, and use a box for glass. Ship with a tracked service and send the tracking number to the lab. Declare the contents accurately and follow the courier’s rules. You are responsible for making sure you may legally send the sample to the lab. More: how to send peptides for testing, where to test peptides for parcels from abroad, and anonymous peptide testing.

Step 7: chain of custody at the lab

Chain of custody is the record of who held the sample, when, and in what state, from your packing table to the instrument. It ties the report to your vial. A careful lab logs the parcel with the date, time and condition, checks the seals against your form, photographs each vial and gives it a lab ID. It then records storage, preparation, measurement, and whether the rest is retained or disposed of.

Compare the lab’s photo with your own: cap colour, fill level and printed lot should match. If they do not, raise it before the report is issued. How it works shows these steps at our lab.

Step 8: get the results and read them

Published turnaround for the standard identity, purity and content test varies by lab. In September 2026 it was an average of 1–3 business days at Freedom Diagnostics and 9–11 business days at ACS Peptide Testing Labs. Add shipping and log-in. Sterility under USP <71> takes at least 14 days at any lab, because the method incubates for 14 days. Lab-by-lab figures: how long peptide testing takes.

Read each number with its method, unit and basis:

• Identity. The observed mass should match the expected mass within the stated error. A plain “conforms” is weaker evidence. See LC-MS identity.
• Purity. A share of UV peak area. It says nothing about water, salts, endotoxin or microbes.
• Content. Check the basis. Net peptide as free base leaves out counter-ions and water; total powder reads higher. About 40% of the certificates Peptigrity held in September 2026 were above 110% of the label, and it does not show such results as good, because gross-powder reporting inflates them. See net peptide content.
• Endotoxin. EU per mg and per vial, with the limit of quantitation. A research peptide has no labelled dose, so no official limit applies; a printed limit should say whose it is.
• Sterility. The method, the 14 days and the units tested. The result covers only those units.

A report describes only the vials the lab received. Our page on how to read a COA explains each part, and the example report shows a full one.

Step 9: verify the report before you share it

Type the lab’s web address yourself, open its lookup page and enter the report number and key (at Janoshik, a task number and a unique key). Then match the lab’s copy to yours: product, lot, dates, results and vial photo. A report you cannot find on the lab’s own site is not verified. The full check: how to verify a peptide COA. When you share a result with a seller or a group, give them the report ID and key so they can check it themselves.

Three routes: individuals, group organisers and brands

	Individual buyer	Group organiser	Brand or vendor
Who picks the vials	You, from your own stock	The organiser, at random from several kits	Random sealed vials from each lot
Usual tests	Identity, purity, content	The same, plus vial-to-vial consistency	Identity, purity, content, endotoxin, sterility, vial-to-vial consistency
Name on the report	The name you give the lab	The group’s name	The brand’s name
Next guide	Vendor COA vs your own test	Run a group test	Vendor batch testing

Individuals. If cost stops you, a group test splits one lab order among buyers of the same batch, and some services test for free: see free peptide testing.

Group organisers. Settle the batch, the tests and the lab before you collect money, and confirm that the seller accepts that lab’s results. Put content in mg on the order, or the group cannot tell whether vials are under-filled. Janoshik, for example, arranges group tests through its contact form, because its online shop cannot split a payment. The group test checklist lists what organisers forget.

Brands and vendors. Test every lot and print the batch ID on the vial. Rating sites score how you test. Disclosed Labs gives 40% of a vendor’s grade to safety-panel coverage. Merit Verified’s vendor score gives more points when certificates come from two or three different labs. Peptigrity does not accept a vendor’s in-house testing.

What HK Analytical does at each step

Quotes are on request at /quote. Group tests go through group testing, and brands can arrange batch testing through /vendors. One order can hold any mix of our tests, per sample: identity (LC-MS), purity (HPLC), content per vial, blind GLP-1 identification, endotoxin (LAL), Sterility (USP <71>, 14 days), residual solvents, counter-ion (TFA, acetate), water content (Karl Fischer) and vial-to-vial consistency. The report carries our own photo of the vial as received.

Results within days of receipt. Sterility (USP <71>, 14 days) is the one test that takes 14 days, because the method incubates for 14 days. Every number comes with its raw data: chromatograms and spectra. The report is a signed record (an Ed25519 signature over the canonical record) and states, inside that record, how the client is related to HK Analytical. Each report has a private link and can be checked at hkanalytical.com/verify. Reports are never edited after issue: a change makes a new version, and the old one is marked superseded. We do not hold ISO/IEC 17025 accreditation.