Peptide Testing Explained: Identity, Purity and How to Read a COA

What Is Peptide Testing?

Peptide testing is laboratory analysis that answers two separate questions about a sample. First, identity: is this actually the molecule on the label. Second, purity: how much of the sample is that molecule rather than impurities and breakdown products. The peer reviewed literature frames peptide quality the same way, as identity, purity and strength assessed with a battery of analytical methods keyed to well characterized reference standards. [11]

Those two questions map to two different instruments, and the order matters: identity is read first, because a purity figure is only meaningful once you know which molecule is being measured. This page is the umbrella explainer. If you want the ranked directory of labs, see our peptide testing labs directory; if you are choosing between them, see our comparison of testing labs.

Identity vs Purity: Mass Spectrometry vs HPLC

Purity is measured by HPLC. Reversed phase HPLC separates the target peptide from impurities and breakdown products and reports the main peak as a percentage of the total. It has been the versatile workhorse for peptide isolation and purity for decades. [13] Vanguard runs the sample on a reversed phase C18 column and determines purity by comparing peak areas to a standard; ILS uses reversed phase HPLC with UV detection at 214 nm or 220 nm as its standard purity technique. [4][5]

Identity is confirmed one of two ways, and labs differ. It can be confirmed by mass spectrometry, which measures the molecular weight and matches it to the value calculated from the sequence, described in the literature as the optimal method for evaluating synthetic peptide authenticity and integrity. [12] MZ Biolabs pairs HPLC with mass spectrometry, and Freedom Diagnostics states plainly that "HPLC confirms purity. LC-MS confirms identity. We never issue one without the other". [6][7] Alternatively, identity is confirmed by HPLC matched to a certified reference standard: Vanguard's published COA confirms identity by HPLC returning "Pass - Matches Ref. Standard", and ILS sells LC-MS identity as a separate custom add-on on top of its HPLC panels. [4][5] At Janoshik, the community default lab, every peptide test lists HPLC only, with identity, amount and purity all read from that one run, and mass spectrometry sold separately to screen for contamination. [3]

This is why identity comes first. ILS notes that HPLC purity alone cannot confirm identity, because a peptide missing a single amino acid can behave similarly on HPLC while being a different molecule; Colmaric makes the same split, with mass spectrometry verifying molecular weight and structure while HPLC gives the detailed purity picture. [5][8] ILS also notes that research grade peptides typically range from 70% to over 98% purity depending on the intended application, so a purity figure is read against what the compound and its use call for, not a single universal cutoff. [5] Whether the vial claims to be BPC-157 or anything else, the two figures only mean something together.

What Does a Certificate of Analysis Contain?

A certificate of analysis, or COA, is a batch specific report that names the issuing lab and records the compound, the lot, the methods and the results. Two fully published real reports show the field set clearly. Vanguard's BPC-157 certificate names the lab and its Olympia, Washington address and lists "Compound: BPC-157", a quantity of 10 mg, a Laboratory ID, a "Lot Number: CHANGSHA-BPC10-0726" and a "Date Reported: 8/3/2026", over a three column Analysis, Method and Result table. On that table identity reads "Pass - Matches Ref. Standard", chromatographic purity reads "99.39% + 0.18%", quantity reads "10.07 mg", endotoxins read "Pass - 5.04 EU/mg" and sterility reads "Pass - Negative for Growth". [4]

A Freedom Diagnostics certificate for Melanotan 2 carries an Accession Number, a Search Code, the client, the product with its mg strength, a lot, a net peptide content in mg, a purity percentage and an identity line: on that specimen, purity reads "99.934%", net peptide content reads "5.86 mg" and identity reads "Melanotan-II". [7] Units are consistent across reports: purity in percent, sometimes with a tolerance such as "99.39% + 0.18%", quantity or net peptide content in mg, and endotoxin in EU/mg. [4][7]

A "pass" is defined against a stated threshold, not left implicit. Vanguard footnotes its endotoxin pass criterion as "*Pass/Fail criteria based on the USP/FDA threshold of 5 EU/kg (350 EU total for a 70 kg adult)", and ILS shows a pass or fail badge for every analyte on its verified report. [4][5] One distinction worth keeping: net peptide content is not the same as purity. It is the actual peptide mass excluding water, salts and counterions, which is why lyophilized powder can weigh more than the peptide it contains. [7][5]

What a COA Proves and What It Does Not

A COA proves what the listed tests found in the one sample the lab received. It is deliberately narrow, and the labs say so:

Read together, those limits explain why a single purity figure is not the whole story, and why a document alone, however polished, is not the same as verification. Our explainer on why a COA matters makes the broader case for treating this report as the baseline, not the finish line.

How Do You Verify a Report Against the Lab That Issued It?

The strongest verification is a live lookup keyed to a unique per report identifier, not a forwarded PDF or screenshot. Several labs run public or semi public lookups:

A lookup that resolves confirms one specific sample on a specific date, with a record that lives on the lab server and cannot be edited after release. Then match the report to your vial: the batch or lot number on the report must match the number on the vial, and the submitter named should be the vendor you bought from. As one lab explainer puts it, the batch or lot number on the report must exactly match the batch number printed on the vial label you received; if they do not match, the report is for a different batch than the vial in your hand. [14] For a single lab worked through end to end, see our Janoshik testing guide.

A trustworthy report also sits inside a standards framework. ISO/IEC 17025 is the international standard for the competence of testing and calibration laboratories, and analytical methods are validated against USP General Chapter 1225, whose validation characteristics include accuracy, precision, specificity, detection limit, quantitation limit, linearity, range and robustness. [2][1] Accreditation is granted by bodies such as A2LA and Perry Johnson: Vanguard is ISO/IEC 17025:2017 accredited through A2LA, and ILS is ISO 17025 accredited; a third party directory lists Colmaric under ISO/IEC 17025:2017 as well, though Colmaric's own site says only that it is ISO/IEC certified. [4][5][8] Not every lab the community uses is ISO 17025 accredited: Freedom Diagnostics describes compliance with ISO 9001 quality management principles and Good Laboratory Practice principles, which is principles language, and a third party directory lists it as not accredited under ISO 17025 while noting a CLIA number. [7]

What Can Home Test Kits Do, and What Can They Not?

Two very different products are sold as "peptide test kits". The first is an at home colorimetric card. VeriPep sells 4-zone colorimetric cards that use amino acid fingerprinting through color reactions, no lab required. At fetch time the product was listed as coming soon on a waitlist, not currently purchasable. Read against the seller's own limitations, the card is a screen, not an analysis:

VeriPep itself tells buyers that for definitive analysis they should submit samples to an accredited analytical laboratory. [9] The second kind of "kit" is really that lab test. Peptide Test sells per compound testing such as a BPC-157 purity and mass test for "$200.00 USD", with HPLC purity and potency methods described as validated according to USP General Chapter 1225, where after checkout you receive shipping instructions for sending in your compound. [10] That is not a home device: it is commissioning an independent lab, covered next.

What Do Peptide Tests Cost, and How Long Do They Take?

The figures below are each lab's own published prices and turnaround, from records dated between February and September 2026. Fees and timing change, so treat these as the shape of the market, not a live quote, and confirm the current figure on the lab's site before sending anything.

Netting it out, an identity plus purity test runs roughly $180 to $600 per sample depending on how deep the panel goes, with turnaround typically about 2 to 8 days, and sterility adding about 14 days. [3][4][5][7] Add on tests published by these labs include endotoxins, heavy metals, bioburden and sterility, each priced separately. Janoshik lists a standalone contamination screen at $170.00, and rush service, where offered, runs from a 50 percent surcharge at Colmaric to a 100 percent surcharge at Janoshik. [3][8]

Vendor COA vs Your Own Test: When Does Commissioning One Make Sense?

Because a report reflects only the sample the lab received, and the lab does not control how that sample was chosen, a seller supplied COA structurally proves less than a buyer commissioning a test of the vial actually received. That is the whole distinction, and a third party editorial puts it plainly: a supplier COA is not the same thing as independent verification. [15]

Vendor commissioned testing, where the seller pays a lab, is still common and is what "third party tested" usually means. The report names the submitting company: Freedom Diagnostics states its COA lists only the company or organization name entered at intake, and Janoshik's public database attributes each result to the submitter while stating it does not endorse, sponsor or have any affiliation with the companies or products listed. [7][3] A real vendor certificate records the vendor as the client: an MZ Biolabs report for semaglutide names the client as the seller, not the buyer, and the vendor advertises it as third party tested by an independent lab. [6] Customer commissioned testing, where the buyer mails in the vial actually received, is the stronger form, because the result belongs to that buyer's specific vial and batch rather than a report the seller chose to show. The same mail in mechanism serves it. [4][5][7]

Community practice, as forum opinions rather than lab statements, tracks the same tension: buyers weigh trusting a supplier COA against paying for their own test. One r/Peptides user describes a source that offers store credit to people who send products in for testing; others caution that anyone can post a bogus test, and one reported a self commissioned result where the worst quantity was 30 percent short. [17] So commissioning a test makes sense when the cost of a bad vial outweighs the roughly $180 to $600 the test costs: a first order from a new supplier, a high value order, a new batch of something you retest routinely, or any case where the paperwork you were shown cannot be verified against the issuing lab. An at home colorimetric card can be a cheap first screen, but it is explicitly not a substitute for lab HPLC or MS. [9]

Frequently Asked Questions

References

Note on sourcing: this page makes no first hand claim about any specific lab's current accreditation, pricing or any product's test result, because those change and must be confirmed with the lab directly. Prices and turnaround are named as each lab published them on the dates cited. Peptides Vietnam has not commissioned any test shown here. The standards references describe how analytical testing is validated and how laboratory competence is assessed, which is the framework a trustworthy COA sits inside.