Receiving a COA from a peptide supplier is only useful if you know what each section means and what questions it answers. A COA that looks comprehensive can still be inadequate if the right tests are missing, the lot number does not match your vial, or the issuing laboratory cannot be independently verified. This guide walks through every section of a real research peptide COA — using Patriot Peptides’ BPC-157 batch documentation as the working example — so you know exactly what you are looking at and what conclusions you can draw from each data point.
If you are new to COA documentation, start with What Is a Certificate of Analysis for the foundational concepts before working through this step-by-step reading guide.
What it shows: The first section of any peptide COA identifies the compound being tested. This includes the compound name, lot or batch number, analysis date, CAS number, and the client or company who submitted the sample for testing.
On the Patriot Peptides BPC-157 COA:
Compound: BPC-157
Lot Number: 00177
Analysis Date: June 8, 2026
CAS Number: 137525-51-0
Client: Patriot PeptidesWhat to check: Confirm the compound name matches what you ordered. Confirm the CAS number matches the known CAS number for that compound — for BPC-157, the correct CAS number is 137525-51-0. A mismatched CAS number is a serious red flag indicating either a labeling error or a different compound entirely.
Most importantly, match the lot number on the COA to the lot number printed on your vial. A COA with a different lot number does not apply to the vial in your hand regardless of how good the results are.
What it shows: The purity percentage is the single most referenced data point on a peptide COA. It represents the percentage of the total detected material in the sample that is the target compound, as determined by HPLC-UV analysis.
On the Patriot Peptides BPC-157 COA:
Purity: 99.10%
Method: HPLC-UV-MSWhat to check: Research-grade peptides should show at least 98% purity. Premium research suppliers target 99% or above. A purity result below 98% from a supplier claiming research-grade quality is a significant concern.
The testing method matters as much as the number. HPLC-UV is the standard quantification method for purity — it measures the area under each peak in the chromatogram and calculates what percentage of the total peak area belongs to the target compound. A COA stating purity was measured by mass spectrometry alone is not using the standard purity quantification method — mass spectrometry confirms identity, not purity percentage.
What it shows: Below the purity percentage, a properly detailed COA includes a peak table — a list of every chromatographic peak detected in the sample, with its retention time, area, and area percentage.
On the Patriot Peptides BPC-157 COA:
Peak Time (min) %Area Assignment
1 5.21 99.10 BPC-157
2 5.43 0.52 —
3 5.66 0.38 —What to check: The main peak — assigned to the target compound — should account for at least 98% of the total peak area. The remaining peaks are impurities. On the BPC-157 COA, the main peak at 5.21 minutes accounts for 99.10% of the total area. The two minor peaks at 5.43 and 5.66 minutes account for 0.52% and 0.38% respectively — both well within acceptable impurity limits.
The retention time of the main peak should be consistent with the expected retention time of the compound under the stated chromatographic conditions. If the retention time shifts significantly between batches using the same method, it may indicate a change in compound identity or chromatographic conditions.
Unlabeled impurity peaks — shown as “—” rather than a named compound — are normal in peptide chromatography. Small impurity peaks from synthesis byproducts are expected and acceptable at these levels. What is not acceptable is a large unlabeled peak that represents a significant percentage of the sample.
What it shows: A properly structured COA includes confirmation that the stated quantity of compound is present in each vial, not just that the sample is pure.
On the Patriot Peptides BPC-157 COA:
Measured Quantity (HPLC-UV): 5.00 mg/vialWhat to check: Confirm the measured quantity matches the labeled quantity. Under-filling — where a vial labeled as 5mg contains significantly less than 5mg of compound — is a real quality issue that purity testing alone does not catch. A 99% pure compound that contains only 3mg of material in a 5mg-labeled vial is delivering 40% less compound than stated regardless of its purity.
What it shows: Mass spectrometry confirms the molecular identity of the compound by measuring the mass-to-charge ratio of ionized sample molecules. The result is compared to the expected monoisotopic mass of the target peptide — the theoretical mass calculated from the compound’s amino acid sequence and molecular formula.
On the Patriot Peptides BPC-157 COA:
Identity (HPLC-MS): Conforms
Expected Monoisotopic Mass: 1418.70 Da
Measured Monoisotopic Mass: 1418.71 DaWhat to check: The measured monoisotopic mass should match the expected reference mass within accepted analytical tolerance — typically within 0.02 Da for high-resolution mass spectrometry. On the BPC-157 COA, the measured mass of 1418.71 Da matches the expected 1418.70 Da with a difference of 0.01 Da — well within tolerance.
The “Conforms” conclusion means the laboratory has confirmed the compound’s molecular identity matches BPC-157. A “Does Not Conform” result would indicate either the wrong compound or a compound with structural modifications that change its molecular weight.
This section is what separates a complete COA from an incomplete one. HPLC purity confirms a compound is present at a high percentage — but it cannot confirm what that compound is. Mass spectrometry provides that confirmation. A COA without mass spectrometry identity data is missing the test that catches mislabeled or substituted compounds.
What it shows: The final section identifies who performed the testing, where, and the overall conclusion.
On the Patriot Peptides BPC-157 COA:
Conclusion: The tested sample conforms to the
Enterprise Standard.
Performed by: Patriot Research & The BioCraft Lab
Contact: info@patriotpeptides.com
Location: Kansas City, Missouri
Affiliated with: Stratton Lab Inc, Manhattan,
New YorkWhat to check: The laboratory issuing the COA should be a real, independently verifiable analytical laboratory. Search the laboratory name and confirm it operates as an analytical testing entity. For Patriot Peptides, testing is performed by The BioCraft Lab affiliated with Stratton Lab Inc — an independent analytical laboratory with verifiable contact information separate from the supplier.
The conclusion statement — “conforms to the Enterprise Standard” — is the laboratory’s formal determination that all tested parameters met the specified acceptance criteria. This is the summary result that the purity, quantity, and identity sections support with their detailed data.
When you receive a COA for any research peptide, work through these checks in order.
Compound name and CAS number match what you ordered. Lot number on the COA matches the lot number on your vial. Analysis date is recent and consistent with the batch you are receiving. Purity percentage is 98% or above with HPLC-UV listed as the method. Peak table shows the main compound peak at 99% or above of total peak area. Measured quantity per vial matches the labeled quantity. Mass spectrometry identity confirms the measured monoisotopic mass matches the expected reference mass. The issuing laboratory is independently verifiable as a real analytical testing entity separate from the supplier.
If any of these checks fail, contact the supplier before using the compound in a research protocol.
A COA is a snapshot of one batch at one point in time. It confirms the compound’s quality at the time of testing — it does not guarantee that quality is maintained if the compound is improperly stored after testing. A 99% pure peptide that is stored at room temperature rather than -20°C will degrade over time regardless of what its original COA showed.
A COA also does not account for contamination during shipping or handling after the sample leaves the laboratory. Proper storage and handling from receipt through reconstitution is the researcher’s responsibility. For guidance on maintaining compound integrity after receipt, see our Research Peptide Storage and Handling guide.
Batch-specific COAs for all Patriot Peptides compounds — covering HPLC purity, mass spectrometry identity, quantity per vial, and laboratory conclusions — are available on our Certificates of Analysis page. Each COA is from an independent certified third-party laboratory and is tied to a specific lot number so you can match your vial’s documentation precisely.
Browse independently tested research compounds in our Research Compounds catalog.
How do I read a peptide COA?
Start with compound identification — confirm the name, CAS number, and lot number match your order and your vial. Check the purity percentage — 98% or above by HPLC-UV is the research-grade standard. Review the peak table and confirm the main compound peak accounts for at least 98% of total peak area. Check the mass spectrometry section and confirm the measured monoisotopic mass matches the expected reference mass within 0.02 Da. Confirm the issuing laboratory is independently verifiable as a real analytical testing entity.
What is the peak table on a peptide COA?
The peak table lists every chromatographic peak detected in the HPLC analysis, with each peak’s retention time, area, and percentage of total area. The main peak assigned to the target compound should account for at least 98% of the total area. Minor peaks are synthesis impurities — acceptable at low percentages, concerning if large or unlabeled at significant percentages.
What does monoisotopic mass mean on a peptide COA?
Monoisotopic mass is the theoretical molecular weight of a compound calculated using the exact atomic masses of the most abundant isotope of each element in its molecular formula. On a COA, the expected monoisotopic mass is the calculated reference value for the target peptide. The measured monoisotopic mass is what the mass spectrometer recorded for the tested sample. When the two values match within analytical tolerance — typically 0.02 Da — identity is confirmed.
What does “Conforms” mean on a COA?
“Conforms” in the identity section of a peptide COA means the measured monoisotopic mass of the tested sample matches the expected reference mass for the target compound within accepted analytical tolerance. It is the mass spectrometry identity confirmation result — a binary conclusion that the compound is what it is claimed to be.
Why does the COA show minor peaks besides the main compound?
Minor peaks in the HPLC chromatogram are synthesis impurities — small amounts of byproduct compounds that remain after peptide synthesis and purification. At low percentages such as 0.52% and 0.38% as shown on the BPC-157 COA, these are normal and acceptable. The purity percentage reflects the main compound peak as a percentage of all peaks combined.
Where can I find Patriot Peptides COAs?
Batch-specific COAs for all Patriot Peptides products are available on our Certificates of Analysis page. Each covers HPLC purity, peak table, quantity per vial, mass spectrometry identity, and laboratory verification. For laboratory research use only.
All Patriot Peptides products are strictly for laboratory research use only. Not for human consumption, veterinary use, or clinical application.
Related reading: What Is a Certificate of Analysis? | How Peptide Purity Is Tested | Research Peptide Storage and Handling | Certificates of Analysis