How to Read a COA? HPLC, MS, and Salt Forms Explained
The COA (certificate of analysis) is the core document for judging peptide quality. Understanding the report matters more than listening to marketing claims.
The Fields That Matter Most
Section titled “The Fields That Matter Most”| Field | Meaning | What to check |
|---|---|---|
| Identity | Identification | HPLC retention time, MS molecular weight |
| Purity | Purity | HPLC area percentage (research grade commonly ≥98%) |
| Quantity | Assay / fill | Actual mg vs label claim |
| Counter-ion | Salt form | Acetate, TFA salt, etc. |
| Water / Residual solvents | Water / residues | Whether limits are exceeded |
| MS (m/z) | Molecular weight | Deviation from the theoretical value |
How to Interpret HPLC Purity
Section titled “How to Interpret HPLC Purity”- High area-normalized purity does not guarantee adequate content.
- Impurity peak positions can point to degradation products or deletion-sequence impurities.
- Read it together with MS identification to avoid “high purity but not the target compound”.
What to Look for in Mass Spectrometry (MS)
Section titled “What to Look for in Mass Spectrometry (MS)”- Whether the observed molecular weight is close to the theoretical [M+H]⁺.
- Whether the isotope distribution is reasonable.
- Identity can only be confirmed when the results match the sequence expectation.
TFA Salt vs Acetate
Section titled “TFA Salt vs Acetate”| Salt form | Characteristics |
|---|---|
| Acetate | More common in research raw materials; more discussion of biocompatibility |
| TFA salt | Commonly used in HPLC preparation; TFA residues may affect cell experiments |
The Counter-ion / TFA content values on a report deserve a separate look.
Fake Reports and Red Flags
Section titled “Fake Reports and Red Flags”- Screenshot only — no testing lab, no date, no sample batch number.
- Purity curves look too “perfect”; peak shapes look unnatural.
- The theoretical molecular weight is wrong or inconsistent with the sequence.
- Price far below market with claims of “lab grade 99%+”.
Cross-Checking Reports Against Entries
Section titled “Cross-Checking Reports Against Entries”Once you have a report, match it against the entry specs: Sports Recovery, Metabolism & Weight Loss, etc. For handling, see Reconstitution and Storage.
Cross-Checks Beyond the Report
Section titled “Cross-Checks Beyond the Report”Once you hold a COA, a few quick follow-up checks decide whether and how the report can be used.
Batch Number and Traceability
Section titled “Batch Number and Traceability”The batch number on the report should match the label on the physical item; the testing date and the issuing lab form the minimal traceability set. A “report” that is only a screenshot, without batch number or date, cannot serve as batch evidence. For a first pass on methods and specs see Peptide Basics.
Spec Sheet, Actual Values, and Retesting
Section titled “Spec Sheet, Actual Values, and Retesting”A spec sheet gives the claimed ranges of the indicators; a COA gives the measured results for that batch. Reading both together is what tells you whether the batch meets specification. One conforming batch does not guarantee batch-to-batch consistency, so long-term purchasing can ask for multi-batch data. When disputes arise, retesting a retained sample is common practice, but HPLC conditions differ between laboratories, so results vary and should not be compared rigidly. Spec-code conventions can be cross-checked in blends and specs; transport and storage differences are covered in storage, and route differences in administration routes.
Abbreviations and indicator names on a report can be checked against the peptide glossary; concentration and formulation context for specific ingredients appears in research entries such as GHK-Cu. Citation and evidence-grading policy is in About.
Key References
Section titled “Key References”Product identification and the illicit market: PMID: 24771717.
Related Reading
Section titled “Related Reading”Is 99% Purity Automatically Good?
Section titled “Is 99% Purity Automatically Good?”Purity is an area percentage; it does not represent content or identity. Check MS and Quantity together.
Is a TFA Salt Acceptable?
Section titled “Is a TFA Salt Acceptable?”It is usable for research; TFA residues may affect cell experiments — check the TFA content on the report.
Safety Boundaries and Limitations
Section titled “Safety Boundaries and Limitations”A COA reflects batch testing; it does not guarantee that specifications still hold after transport and storage. Purity values under different HPLC conditions cannot be compared directly. This page is a guide to reading reports, not a quality certification.