Reading a blend ratio verification

A vial containing three peptides raises a question a single-compound certificate never has to answer: are they present in the proportions the label claims?

Two separate questions

Verifying a blend means answering both. First, is each component the compound it should be, at the purity claimed — the same identity and purity work any single peptide requires, repeated per component. Second, are they present in the stated ratio.

The second does not follow from the first. Three individually pure peptides can be combined in the wrong proportions, and nothing about their individual certificates would reveal it.

How ratio is determined

Chromatographically. Because each component has its own retention time, a single run separates them into distinct peaks, and the relative peak areas reflect relative quantities — once corrected for the fact that different molecules absorb UV light to different degrees. That correction matters: raw peak areas would misstate the ratio in favour of whichever component absorbs most strongly.

What to look for

A blend certificate should state the intended ratio, the measured ratio, and the tolerance considered acceptable. It should also give the total mass in the vial, since a correct ratio at the wrong total is still the wrong amount of everything.

One caveat worth naming: combination products of this kind have generally not been characterised as combinations in published research. Verification confirms what is in the vial. It says nothing about how the components behave together.