Why we publish every COA

Most research-peptide suppliers publish a headline purity number on the product page: "99.2% HPLC." Some attach a PDF labeled "Certificate of Analysis" with a few pass/fail lines. A smaller number publish the actual chromatogram. We're in the third group, and we want to explain why.

A headline number is not a measurement

"99.2% HPLC" is what we hand to a buyer at the end of a long chain of decisions made by an analytical lab. That number is correct, but it's the output of methodology choices that could have been made differently. Which solvent system was used? Which integration window? Were any peaks excluded from the integration as "outside the relevant range"? Different methods, different numbers. The same lot might report 98% or 99.5% depending on whose lab ran it and how aggressively they integrated.

Publishing only the headline number obscures all of that. It asks the researcher to trust the methodology unseen.

The chromatogram contains the methodology

When we publish the actual HPLC trace — the full graph of detector signal versus retention time — three things become visible:

• Where the peaks are. If a known impurity should elute at 12 minutes and the chromatogram shows nothing there, that's information. If a small peak appears at 8 minutes and the supplier didn't integrate it, that's information.
• How clean the baseline is. A flat baseline between peaks suggests the column was well-equilibrated and the gradient was appropriate. A drifting or noisy baseline suggests instrument issues that may have affected the integration.
• What was actually counted. Integration markers are typically visible on the trace, showing which peaks the software included in the total area calculation. A reasonable researcher can verify that the integration looks honest.

You can extract a number from the trace. You can't extract the trace from the number. Publishing the chromatogram is publishing the work.

This matters when batches drift

Every peptide manufacturer's process matures over time. The lot you receive in January and the lot you receive in October come from the same target compound but may not have identical impurity profiles. If you're running a multi-month study, that drift matters — small changes in impurity distribution can affect sensitive in-vitro assays.

When the COA is just a headline number, "99.2% then" and "99.2% now" look identical even when the underlying chromatograms differ. When we publish the trace, you can compare January's chromatogram to October's and see whether the impurities are stable. You can flag a lot for sensitive work if the profile changed. We've had researchers do this — surface a question we hadn't anticipated, prompted by a comparison we couldn't have made internally.

The cost of publishing

It's worth being honest that publishing every chromatogram has a cost. It exposes the methodology to scrutiny that some labs would prefer to avoid. It makes us accountable for the integration choices in a way a single number does not. It also means the COA PDFs are larger, take a bit longer to render, and are more work to keep linked correctly across lots.

We made the trade because the alternative is worse. The alternative is asking researchers to take our word for it. Our word, with no underlying data, is worth no more than any other supplier's word. The chromatogram is what makes the word meaningful.

What this looks like in practice

On every product page, the "Certificate of Analysis" link opens a PDF that includes:

• The full HPLC chromatogram for the current shipping lot
• The mass spectrum confirming peptide identity
• Endotoxin (LAL) result with the actual EU/mg number
• Microbial bioburden values
• The method block specifying instrument, column, gradient, detection wavelength
• Third-party laboratory name and signature

After purchase, the COA for your specific lot is permanently linked to your order. You can verify the lot number against the vial and re-download the COA any time.

What we hope happens

We hope this practice becomes standard. A peptide research supplier that won't show you the methodology is selling a number, not a measurement. Researchers deserve the measurement. The chromatograms get published every lot because if we're asking you to put a compound into your experimental model, the least we can do is show our work.

This is an opinion piece reflecting Merit's quality position. It is not investment advice, regulatory guidance, or a research protocol recommendation.