Every peptide we ship has been independently tested using high-performance liquid chromatography (HPLC) and mass spectrometry. Here is exactly what we test for, how we test it, and what the results mean.
Most peptide suppliers purchase from the same upstream manufacturers. What separates a reliable source from a risk is whether they independently verify what they received — and whether they share those results openly.
Unverified batches frequently contain synthesis byproducts, residual solvents, or incorrect isomers. These do not show up in appearance or smell — only in analytical testing.
Without independent verification, you are relying on manufacturer self-reporting. Third-party HPLC testing closes this loop — our lab tests, not the manufacturer's.
Impure compounds introduce variables that invalidate results. If you are running a controlled experiment, known purity is a prerequisite, not an optional nice-to-have.
Mass spectrometry confirms that the compound matches its theoretical molecular weight — ruling out substitution with cheaper or structurally similar alternatives.
High-performance liquid chromatography separates the components of a dissolved sample as they pass through a stationary phase at high pressure. The result is a chromatogram showing every compound present by retention time and relative concentration.
How purity is calculated: The HPLC detector (typically UV at 220nm) measures the area under each peak in the chromatogram. Purity percentage is the target compound's area divided by the total area of all peaks. A result of 99.1% means 99.1% of what was detected is the target peptide — the remaining 0.9% are identifiable trace compounds.
Mass spectrometry as confirmation: HPLC tells us relative abundance. MS tells us molecular identity. Every batch is additionally confirmed by electrospray ionization mass spectrometry (ESI-MS), matching the observed molecular ion [M+H]+ against the theoretical mass of the target peptide sequence. A purity result without MS confirmation leaves room for a structurally similar compound to inflate the main peak.
The threshold: We require ≥98% HPLC purity on every batch before it ships. Batches below this threshold are rejected and returned to the manufacturer. The COA included in every shipment reflects the actual test result, not a minimum specification.
Every batch goes through the same documented chain from receipt to shipment. Nothing ships without a complete paper trail.
Raw peptide arrives from the upstream manufacturer. The batch is logged with supplier lot number, receipt date, and quarantine status. Nothing enters inventory at this stage.
A representative sample is pulled from the batch and sent to our contracted third-party analytical laboratory under chain-of-custody documentation. The remaining batch stays quarantined.
The lab runs reversed-phase HPLC and ESI-MS on the sample. Results include the full chromatogram, peak table, identified impurities, molecular ion confirmation, and purity percentage.
We review results against our ≥98% purity floor and confirm molecular identity. Failing batches are rejected and returned. Passing batches are approved for release.
The certificate of analysis is generated with the actual test data — lab name, accreditation, lot number, purity result, MS confirmation, and test date — and linked on the product page.
A printed copy of the batch-specific COA ships with every order. The document you receive corresponds to the exact lot number on your vial, traceable back to the original test.
A certificate of analysis is only useful if you can read it. Here is what each standard field indicates and what to look for.
| Field | What It Tells You |
|---|---|
| Compound Name / CAS | The full IUPAC name and CAS registry number of the compound tested. Confirms you have the right molecule — cross-reference CAS against an independent database if you want to verify. |
| Lot Number | The manufacturer batch identifier. This is the traceability link — your vial's lot number should match the COA exactly. Mismatched lot numbers mean the COA does not apply to your sample. |
| HPLC Purity % | The primary result — percentage of detected signal attributable to the target compound. Our minimum is 98%. The result shown is the actual measured value, not a rounded or estimated figure. |
| Molecular Weight (MS) | The observed molecular ion from mass spectrometry, compared to theoretical MW. Confirms compound identity. A purity number without MS confirmation is insufficient for research applications. |
| Test Date | When the analysis was performed. Peptide stability varies by compound and storage conditions — test date helps you determine whether the COA reflects current batch condition or an older result. |
| Laboratory / Accreditation | The name, location, and ISO/IEC 17025 (or equivalent) accreditation of the testing facility. Accreditation means the lab's methods have been independently audited. Unaccredited labs have no external validation of their procedures. |
| Chromatogram | The raw output of the HPLC run. A genuine COA includes the actual chromatogram — a graph of detector response over time. Inspect it for unexpected peaks. A clean chromatogram shows one dominant peak; multiple large peaks are a red flag regardless of the reported purity number. |
Not all COAs are equal. Some are fabricated; others are real but inadequate. Here is what to look for when evaluating any supplier's documentation.
Every product in our catalog has its batch-specific certificate of analysis linked directly on the product page. No request needed — it is public by default.
Browse Peptide Catalog →