Peptide Compass · Research
How to read a peptide COA: purity, amount and identity
“99% pure” sounds definitive. Without the method, batch attribution and an amount measurement, much remains unclear. A certificate of analysis, or COA, becomes useful when you read its tests separately.
Three questions, three different checks
Identity: what was detected?
Identity tests compare characteristic sample properties with a reference. A report may use spectra or retention times, for example. One method may not distinguish every similar substance.
Purity: what does the measurement profile show?
Chromatographic purity describes the relationship between evaluated signals under the stated measurement conditions. It is not a blanket assurance that every possible impurity has been excluded.
Amount: how much was measured?
An amount determination or assay may report a value in mg. Total powder weight, compound amount and purity percentage are not the same. Water, salts and additives can contribute to total weight.
A real COA example
Particle Peptides links a Liquilabs BPC-157 report in its COA Vault. The document illustrates why amount and purity need separate interpretation. The supplier is our partner; this example is not a product recommendation.
Liquilabs · BPC-157 · 21.10.2026
- Batch in PDF
- 2026359
- Measured amount / assay
- 10.83 mg [±0.05]
- Purity
- 98.4% [±0.5]
- Identity tests
- FTIR · RT
Values transcribed from the linked original, cover and results page. This is not a laboratory certificate issued by us. Bracketed values are reproduced from the report.
The vault uses PO-2026359; the PDF states 2026359. This does not establish the batch on a particular vial. Attribution must be checked against the actual label.
How to check a report
Match the sample
Compare product name, batch, sample identifier and date. A report for a different batch is not evidence for the listing you are assessing.
Open the original
Open the complete document and a laboratory verification page where available. A cropped image may omit methods, limitations or other findings. A logo alone does not establish authenticity.
Read the method and unit
Check whether a value is expressed as a percentage, mg or another unit. Match it to the actual test. “Pass” is meaningful only in relation to the test target and limit.
Identify the gaps
When a result is absent, record it as “not established”. Missing information proves neither a pass nor a failure.
What even a detailed COA cannot establish
A report initially concerns the tested sample. It does not automatically establish who collected it, whether it represented the whole batch or how each later vial was stored. These are questions of sampling, traceability and supply chain.
Purity testing, microbial counts and endotoxin testing are also different investigations. One result cannot stand in for a test that was not performed. A COA is not a clinical safety assessment or evidence of medical efficacy.
Common questions about peptide COAs
Does 99% purity mean 9.9 mg in a 10 mg pack?
You cannot make that calculation without additional information. A chromatographic percentage is not automatically the mass fraction of the entire powder. Establishing the amount requires an appropriate quantitative measurement.
Does HPLC automatically establish identity?
No. The procedure, references and interpretation matter. Retention time, spectra and additional methods provide different information. Read which identity test the report actually lists.
Is a COA link enough to establish a good supplier?
It is one piece of evidence. Traceable batch attribution, verifiable company information, clear pricing and shipping terms also matter. A partnership with our portal replaces none of these checks.
Where to go next
Sources and review date
Editorial source check: 30 October 2026. Shop information is supplied by the respective vendor. Linked laboratory reports were reviewed as documents; we did not collect or analyse the samples.
Created with AI assistance. This new edition has not yet received independent editorial review.