Full panel peptide test: what each test answers, and which ones you can skip

What a full peptide test panel includes

A full peptide test panel answers four questions about a vial: what is in it, how much, whether there is microbial contamination, and what else is in the powder or the batch. Ten tests cover those questions. Few buyers need all ten on every vial.

Test	Question it answers	Reported as	What it cannot tell you
Identity (LC-MS)	Is the main peptide the one on the label?	Measured mass against expected mass	Purity, amount, or same-mass isomers
Purity (HPLC)	What share of the UV-absorbing material is the target peptide?	% of peak area at a stated wavelength	Water, salts, endotoxin, microbes or mg
Content per vial	How many mg of the peptide are in this vial?	mg as free base against a reference standard, with uncertainty and % of label	Whether other vials hold the same
Blind GLP-1 identification	Which GLP-1 family peptide is in the vial, or a mix, if the lab is not told the label?	Each listed candidate found, and how much	Peptides that are not on the candidate list
Endotoxin (LAL)	How much bacterial endotoxin is in the vial?	EU per mg and EU per vial; “less than” the limit when below it	Whether live microbes are present
Sterility (USP <71>, 14 days)	Did microbes grow from the tested units in at least 14 days?	Growth or no growth in the tested units	That the whole batch is sterile
Counter-ion (TFA, acetate)	How much of the powder is TFA or acetate salt?	Share of the powder	Toxicity at a given use
Water content (Karl Fischer)	How much of the powder is water?	% of the powder	Peptide identity or purity
Residual solvents	Which solvents are left from synthesis or purification?	Named solvents	Peptide identity or amount
Vial-to-vial consistency	Do vials of one batch hold the same amount?	Content per vial for n vials, with mean, range and RSD	Vials the lab did not receive

The core three usually share one sealed vial; endotoxin, sterility and consistency need more. See how many vials to send.

How a medicine specification compares

For a medicine, ICH Q6A names four universal tests for a drug substance: description, identification, assay and impurities. The EMA guideline on synthetic peptides, in force since 1 June 2026, also lists counter-ion content, residual TFA, water, residual solvents, bacterial endotoxins and microbiological purity. The EU assessment report for Liraglutide Stada, an authorised GLP-1 medicine, shows a real case. Its active-substance specification includes identification by monoisotopic mass and HPLC, water, acetic acid and TFA, related substances, oligomers, the amino acid ratio, assay, residual solvents and bacterial endotoxins.

A research peptide has no official specification, so no list is “required”. The ten tests above follow the same logic, and a few medicine items sit outside them, such as oligomers, the amino acid ratio and sequence confirmation.

The core three: identity, purity and content

These three answer whether the vial is what the label says, so every panel starts here.

Identity needs a mass. ICH Q6A states that identification by a single chromatographic retention time “is not regarded as being specific”. A mass match shows which molecule is there: see HPLC vs mass spec.

Purity and content are two numbers. Purity is a share of UV peak area. Content is mg of peptide against a reference standard. A vial can read 99% pure and still hold well under its labelled mg of peptide, because the powder also holds salt and water. Net peptide content walks through the arithmetic.

Keep content on the order. In one group test reported on Reddit, a CJC-1295 and ipamorelin blend was ordered without it. The group got percentages with no mg, so nobody could tell whether the vials were under-filled.

When blind GLP-1 identification fits better

Standard identity checks one expected mass: the peptide the client names. Blind GLP-1 identification compares the measured masses with the calculated mass of each GLP-1 family candidate, without the label claim, and reports which one is there, or a mix, and how much. Choose it when the label is missing, when you suspect one GLP-1 was sold as another, or when you want a result nobody could anchor on the label. More in blind GLP-1 identification.

Endotoxin and sterility answer different questions

Endotoxin comes from the outer membrane of Gram-negative bacteria and can be present when no bacteria are alive. The LAL test measures it in EU per mg and EU per vial. Sterility asks whether live microbes grow from the sample. The USP <71> method incubates the tested units for at least 14 days, needs its own unopened vials, and covers only the units tested. A microbial count, a PCR screen or a bioburden test answers a different question and is not a sterility test. See endotoxin vs sterility.

Composition tests: what else is in the powder

Lyophilised peptide powder also holds counter-ion salt from synthesis and purification (TFA or acetate), water, and traces of solvents. They matter most for bulk powder, for a brand qualifying a new supplier, and when a content result disagrees with another lab’s, because they show what the rest of the powder weight is. For context, ICH Q3C limits residual acetonitrile to 410 ppm and DMF to 880 ppm in medicines. DMF is common in peptide synthesis, and acetonitrile in purification.

Which tests to order for which purpose

Your purpose	Order	Add when	Usually skip
Check one vial you bought	Identity, purity, content per vial	Endotoxin and sterility, if your question includes microbial contamination and you have spare sealed vials	Consistency, counter-ion, water, residual solvents
A GLP-1 vial with a doubtful or missing label	Blind GLP-1 identification, purity, content per vial	Endotoxin and sterility	Standard identity, composition tests
Group test of one batch	Identity, purity, content per vial, vial-to-vial consistency	Endotoxin and sterility	Composition tests, unless content results disagree
Seller releasing a finished batch	Identity, purity, content, consistency, endotoxin, sterility	Composition tests for a new supplier or a changed process	Blind GLP-1, unless the label is in doubt
Bulk powder before filling	Identity, purity, content, counter-ion, water, residual solvents	Endotoxin, if the powder will be filled into vials sold as sterile	Sterility and consistency, which need finished vials
A content result that disagrees with another lab	Content per vial	Counter-ion and water, to show the basis	Safety tests, which do not bear on mg

Three rules hold for every row. Identity comes from a mass, never from retention time alone. Content in mg belongs on every order. And purity is not a safety result, just as endotoxin is not sterility. For planning, see how to run a peptide group test and batch testing for vendors.

What “full panel” means at different labs

Packages put different tests under similar names. In September 2026, Finnrick’s community tests covered identity, purity and quantity, its Standard test added endotoxin, and its build-your-own option listed sterility as unavailable. Vanguard’s Silver package covered purity, quantity, identity and solubility from one vial. Its Gold package added endotoxins, bioburden (USP <61>), a fentanyl screen and vial seal integrity, from three vials, and the 14-day USP <71> sterility test was an option at every level. Vanguard’s own site points out that bioburden is not sterility.

Rating sites count the safety tests: Disclosed Labs gives 40% of a seller’s grade to safety-panel coverage, and PeptideTrust scores whether sellers publish sterility and endotoxin results.

A test name on a price list is half the story. Here is what the public certificates we read in September 2026 showed (26 formats: 25 labs and one rating site’s wrapper):

Test	What the certificates showed
Identity	12 of 26 showed a mass spectrum; 3 printed expected and observed mass with an error value
Content per vial	21 of 26 printed mg per vial; 1 stated plainly what the mg meant
Endotoxin	None gave a number on a clear basis (EU/mg or EU/vial) in full; 11 did so in part
Sterility	None showed a documented 14-day USP <71> test with the number of units; the word was used for microbial counts, PCR screens and short cultures
Several vials	6 of 26 printed a separate result for each vial when several were tested

Before you order, ask for a sample report for the exact panel, the method behind each test name and the number of vials. How to choose a peptide testing lab lists the other checks.

What HK Analytical runs in one order

Every test on our test list can go in one order, in any mix per sample. 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, in a signed record you can check at hkanalytical.com/verify. The report carries our photo of the vial as received and, inside the signed record, states how the client is related to HK Analytical. We do not offer blend analysis per component, sequence confirmation, hGH size variants, copper content, bioburden, microbial screens or fentanyl screens. See the example report. You can request a quote, and groups and brands can order through group testing and batch testing for vendors.