What a certificate of analysis actually proves

A certificate of analysis is a one-page summary of what an analytical lab did to a sample and what it found. It is not a guarantee on its own — it is evidence of measurement, and only as credible as the lab that signed it.

An HPLC trace, the dominant chart on most peptide COAs, separates components in a sample by how quickly they move through a packed column. Each component shows up as a peak. The area under the peak is proportional to mass. A clean 99% peak says: 99% of the mass we injected sat at this retention time. It does not say what that mass is.

Identity is a separate test. To prove the peak at minute 7.4 is in fact your peptide, the lab runs HPLC-MS — the same separation, but the column outflow now goes into a mass spectrometer that weighs each fragment. If the measured mass matches the theoretical mass of the target sequence within tolerance, you have identity. Mass = concentration. Identity = what the mass actually is. Both must appear on the COA, or you only know one half of the story.

A third-party lab is one that does not also manufacture the compound. The conflict of interest is obvious — an in-house QA team has every incentive to release the lot. An independent lab does not. The signature on the COA names a human analyst, not a department.

Dates matter for two reasons. First, peptides degrade; an undated certificate could describe a lot tested years before it shipped. Second, the date proves the COA was generated against this batch and not retrofitted from an older test. If the issue date on the certificate is days after the manufacturing date stamped on the vial, the document is doing its job.

When the parcel arrives, the COA should be folded inside the box or accessible by QR. Five things to check: the lot ID on the vial matches the lot ID on the certificate; the compound name and theoretical mass are listed; both purity (HPLC area %) and identity (HPLC-MS observed mass) are reported; the accreditation number and signing analyst are named; and the date of issue is recent and post-dates the manufacturing date.

Every Optimal Lab vial ships with its lot-matched COA, signed by our supplier Janoshik and resolvable from the QR on the label.