Evidence guide · Updated August 25, 2026
How to read a peptide certificate of analysis.
A seven-step method for separating what a COA reports from what a polished document only appears to prove.
BEGIN WITH SCOPE
A COA is evidence about a tested sample—not a universal promise.
A certificate of analysis records results for the sample submitted to a laboratory. Its value depends on traceability, the analytical methods used, the specifications applied, and the categories actually tested.
Start by writing down the certificate number, lot number, product description, laboratory, analysis date, and verification link. Those fields determine whether the document can be connected to the product claim you are evaluating.
Confirm identity separately from purity
Purity estimates how much of the detected chromatographic material belongs to the main peak. Identity asks whether that material is actually the named compound. Look for an explicit identity result and the method used, such as a reference comparison or mass-spectrometry-based analysis.
Does the certificate say identity was confirmed, and how?
Read the method behind the purity percentage
A percentage without a method is difficult to interpret. Look for HPLC or another named analytical method, the detection conditions, a specification, and—when available—the chromatogram. A large main peak does not show that every possible impurity was detectable by that method.
What method produced the number, and what could that method miss?
Separate measured content from the label claim
A vial labeled 10 mg does not mean the laboratory measured 10 mg. Find a net-content, assay, potency, or quantitative result. Then compare the measured result with the label and check whether the report provides an acceptance range or only lists the number as report-only.
Was content measured, or is the certificate repeating the label?
Match the report to one specific lot
A legitimate report can still be irrelevant to the item being shown. Compare the lot or batch number, product description, dates, supplier record, and laboratory verification page. Never extend one tested lot into a claim about all current or future inventory.
Can you connect the tested sample to the exact lot under discussion?
Identify what the sterility result actually represents
If sterility or microbial testing is claimed, look for the method, the acceptance criterion, and the reported result. Different methods answer different questions; a document should make that boundary visible rather than relying on a green pass badge alone.
Which microbial method was used, and what result was reported?
Look for a quantitative endotoxin result
An endotoxin entry is more useful when it includes a named method, numerical result, units such as EU/mL, and a stated specification or reporting limit. A certificate that only says “tested” leaves the actual outcome unclear.
Are the method, number, units, and limit all visible?
List the contaminants that were—and were not—screened
A contaminant panel is never universal. Record the individual metals, solvents, adulterants, or other analytes listed, along with their limits. “Pass” applies only to the analytes and thresholds actually reported.
Which exact contaminants were included in the panel?
FIVE FAST RED FLAGS
Pause when the document cannot be connected to the claim.
- 01A purity percentage with no named analytical method.
- 02No certificate number, lot number, or laboratory verification path.
- 03The supplier name, product, or lot differs from the verified laboratory record.
- 04A label amount presented as though it were a measured-content result.
- 05A single “pass” badge used to imply testing categories that are not listed.
COMMON QUESTIONS
Read the limits as carefully as the results.
Does 99% purity mean a sample is safe?
No. A purity result describes the main analytical signal under a particular method. It does not establish identity by itself, rule out every contaminant, prove sterility, or determine suitability for use.
How can I verify that a COA is authentic?
Use the issuing laboratory’s verification link or QR code when available, compare the certificate number and access code, and confirm the lot and product fields match the record being discussed.
What is the difference between purity and measured content?
Purity describes the proportion of the detected material attributed to the primary analytical peak. Measured content estimates how much target material is present. They answer different questions.
Does Compound IQ independently test every product?
No. Reviews based on public or supplier documents are labeled as document reviews. We identify what those records report and what they leave unknown.
USE THE SAME SEVEN CHECKS EVERY TIME
Scan your next COA, then verify the underlying record.
The quick scan looks for seven evidence signals in your browser. It does not upload the document or decide whether any reported result passed.
FREE TWO-PAGE REFERENCE
Keep the seven checks beside your next COA.
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