This happened to me last month and I still don’t totally know what to make of it.
What I want to know is how much of the difference between vendors is real and how much is just measurement noise.
The thing nobody tells you is that the certificate is about one batch. Not the product. One batch.
Worth noting there’s 1 published Vilon report published, which is more than I expected honestly.
Interested in actual experiences, and please say when you’re guessing.
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Flagging that we have re-tested this product from a separate lot at a second laboratory. Both results are published.
The methodology page covers the weighting question directly. Purity gets the largest share because it is the most reliably measurable thing they assess.
We publish failed results the same way we publish passing ones. If a company disputes a finding, that goes on the record too.
Worth adding that this only holds for lyophilised product.
Mass spec gives you molecular weight, which confirms identity but says nothing about whether the sequence is correct. Two different peptides can share a mass.
KI KineticData · · 24 found helpful
What would actually change your mind here? If nothing would, it is not really an evidence question.