A Certificate of Analysis is one of the most cited — and most misunderstood — documents in the research peptide space. Suppliers present them as quality proof. Communities debate them as evidence of legitimacy. But few resources explain what a CoA actually says, what it cannot say, and what questions it leaves completely unanswered.
This guide walks through a CoA field by field — what each section means, how to evaluate it, and where the genuine limits of this document lie.
What Is a Certificate of Analysis?
A CoA is a document issued by a testing laboratory reporting the results of analytical tests performed on a specific sample submitted to that lab. It is a record of what one test found in one sample on one date.
A CoA does not certify a product. It does not apply to an entire batch. It does not guarantee that another vial from the same supplier, or even another vial from the same order, would produce the same result. It is a snapshot of a single sample under specific testing conditions.
The most important thing to understand about a CoA: it documents what was in the sample that was tested. It says nothing about what is in the vials you did not test.
Third-Party vs. In-House CoAs
Before reading any CoA, the first question is: who issued it?
Third-party CoAs are issued by independent laboratories that have no commercial relationship with the supplier. The lab's only interest is accurate measurement. Examples include Janoshik Analytical, Colmaric Analyticals, and Freedom Diagnostics. Third-party CoAs carry significantly more credibility because the testing entity has no financial stake in the result.
In-house CoAs are produced by the supplier's own testing equipment or an affiliated laboratory. This does not automatically mean the results are false, but the conflict of interest is real — a supplier's in-house lab has commercial incentive to produce favorable results. In-house CoAs should be treated with appropriate skepticism.
A CoA that does not clearly identify an independent laboratory by name and provide verifiable contact information should be treated as an in-house document regardless of what it claims.
Reading the Document: Field by Field
Laboratory Name & Contact Information
Identifies who performed the testing. Should include the lab's full legal name, address, and contact details. A CoA without identifiable lab information cannot be verified and should be treated as unreliable.
Sample ID / Lot Number
A unique identifier for the specific sample tested. This is how the result is tied to a particular submission. Without a sample ID, there is no way to verify that the document corresponds to a real submission to that lab.
Note: some labs allow buyers to verify results using the sample ID on the lab's website. This is a meaningful quality signal — it means the result is independently checkable.
Test Date
When the analysis was performed. A CoA from several years ago may not reflect current production quality from that supplier. Dated results should be interpreted accordingly.
Compound / Analyte Name
What the lab was asked to test for. The lab measures what it was asked to measure — it does not independently determine what is in the sample. If a supplier submits a sample labeled "BPC-157" the lab tests for BPC-157. It will not necessarily detect a substitute compound.
Test Method
The analytical technique used. Common methods include HPLC (High Performance Liquid Chromatography), LC-MS (Liquid Chromatography–Mass Spectrometry), and UV spectroscopy. Each method measures different things and has different limitations. A purity percentage is only meaningful in the context of the method used to produce it.
Purity Percentage
The most commonly cited figure. HPLC purity measures what percentage of the sample's detectable content is the intended compound. A result of 98% means 98% of what the instrument detected was the target peptide — it does not mean 98% of the vial's total content by weight, and it does not detect compounds the instrument was not calibrated to find.
A high purity percentage answers the question "is this compound relatively clean?" — it does not answer "is the right amount of compound present?" Those are separate questions requiring separate tests.
Retention Time
In HPLC testing, each compound moves through the chromatography column at a characteristic speed. Retention time is used to confirm compound identity — the target peptide should appear at a known, predictable retention time. An unexpected retention time is a red flag for the wrong compound or significant impurities.
Molecular Weight / Mass Confirmation
Present on mass spectrometry (MS) results. Confirms the compound's molecular identity by measuring its mass-to-charge ratio. This is the most reliable method for confirming that a compound is what it claims to be, rather than a structurally similar substitute.
Quantitative Amount (mg)
A separate test from purity. Measures whether the stated weight of compound is actually present in the vial. A vial labeled 5mg that contains only 3.2mg is 100% pure but still significantly underdosed. Many CoAs report purity only and do not include quantitative testing — these are two different measurements.
Pass / Fail Designation
A summary judgment against the lab's acceptance criteria. Important to understand: pass/fail reflects the lab's internal standards, which may or may not align with any external standard. A "pass" on purity typically means the result exceeded a threshold set by whoever ordered the test — often the supplier.
Labs test against the specifications they are given. A supplier can set a low acceptance threshold and consistently "pass" results that would fail against a more rigorous standard.
What Most CoAs Do Not Test
Standard peptide CoAs — those typically provided by research suppliers — usually cover purity and identity only. The following tests are rarely included unless specifically requested and paid for separately:
- Endotoxin / LAL testing — detects bacterial endotoxins, relevant for anything intended for injection. Endotoxins can be present even in a high-purity compound.
- Sterility testing — checks for live microorganisms. Separate from endotoxin testing.
- Heavy metals testing — screens for lead, mercury, arsenic, and cadmium contamination from manufacturing processes.
- Residual solvents — manufacturing byproducts that may remain in the finished compound.
- Quantitative amount — as noted above, frequently omitted from standard purity CoAs.
The absence of these tests from a standard CoA does not mean a product failed them. It typically means they were not ordered. Whether that omission is meaningful depends on the intended use.
Red Flags and Green Flags
🚩 Red Flags — Question These
- No laboratory name, address, or contact information
- No sample ID or lot number — results cannot be verified
- No test date, or test date is years old
- Purity figure without a stated test method
- Results from an unidentified or in-house lab
- Identical purity figures (e.g., exactly 99.9%) across multiple different products from the same supplier
- CoA provided as an image file rather than a PDF — harder to verify provenance
- Supplier cannot or will not identify which lab performed the testing
✓ Green Flags — Meaningful Quality Signals
- Named independent third-party laboratory with verifiable contact information
- Sample ID that can be checked directly on the lab's verification portal
- Both HPLC purity and mass spectrometry identity confirmation present
- Test date within the last 12 months
- Quantitative amount testing included alongside purity
- Realistic purity figures — results in the 95–99% range are more credible than uniform 99.9%+ across all products
- Lab report format consistent with the named lab's known document style
The Publication Selection Problem
One question worth holding when reviewing any supplier's publicly displayed CoAs: which results did they choose to publish?
Suppliers who use third-party labs select which results to display on their websites. A supplier with ten test results showing eight passes and two failures has no obligation to publish the failures. The publicly visible CoAs from any supplier represent a curated subset of all testing that has occurred — not a complete picture.
This is not unique to any specific supplier or lab. It is a structural feature of how voluntary testing and self-publication work. Understanding it is part of reading CoA evidence accurately.
For more on this topic, see our analysis of what peptide testing data actually shows.
What a CoA Cannot Tell You
Even a well-documented, third-party CoA with multiple test types has meaningful limits:
- It applies to one sample. It says nothing about other vials, other batches, or future production runs from the same supplier.
- It reflects what was submitted. The lab tests what it receives. There is no independent chain of custody verification between the supplier's inventory and what arrives at the lab.
- It does not address safety for human use. A compound can be analytically pure and still be inappropriate, dangerous, or illegal for human administration.
- It does not address dosing accuracy for any individual. Analytical purity and clinical appropriateness are entirely separate questions.
- It does not account for storage and handling after testing. A product that passed testing at the time of analysis may have degraded before reaching the end user.
Frequently Asked Questions
What is a Certificate of Analysis for a peptide?
A CoA is a document issued by a testing laboratory reporting the results of analytical tests on a specific sample. For research peptides it typically reports purity, identity, and sometimes quantity. It reflects only the sample tested — not the entire batch.
What is HPLC purity and what does it actually measure?
HPLC purity measures what percentage of the sample's detectable content is the intended compound. A 98% result means 98% of what the instrument detected was the target peptide. It does not measure total amount in the vial and does not detect compounds the instrument was not calibrated for.
Does a CoA prove a peptide is safe?
No. A CoA documents analytical test results on a specific sample. It does not address safety for human use, long-term effects, or the full range of possible contaminants. Most standard peptide CoAs do not include endotoxin, sterility, or heavy metals testing.
What is the difference between a third-party and in-house CoA?
A third-party CoA is issued by an independent laboratory with no commercial relationship with the supplier. An in-house CoA is produced by the supplier's own equipment or affiliated lab. Third-party CoAs carry more credibility because the testing entity has no financial incentive in the result.
What are red flags on a peptide CoA?
Key red flags include: no laboratory name or contact information, no sample ID, no test date, purity figures without a stated test method, in-house rather than independent testing, and identical purity figures across multiple different products.
Disclaimer: This article is for informational and educational purposes only. BetterNewLives.com is not affiliated with any testing laboratory or research peptide supplier mentioned on this site. Nothing in this guide constitutes medical, legal, safety, or purchasing advice. Research peptides are sold for laboratory and investigational use only and are not approved for human consumption or self-administration. References to specific laboratories are for illustrative purposes and do not constitute an endorsement of any laboratory's services or results.