Reading a KP certificate: what is on it and what is not

Started 11 March 2025 · 5 replies · 87 hearts · read 1.3k times

TamGlasgow, UK · 11 March 2025

1.4 years ago

I have three KP certificates in front of me and I want to go through what is actually on them, because I spent a year looking at documents like this and taking the big number on trust.

Top line first: the lot code, which is the only thing on the page that connects the document to the vial in my hand. Then the assay method, then the column and the gradient, then the detection wavelength, then the water content. The purity figure comes last on mine and I now read it last too.

The thing I did not understand for a long time is that the figure is a proportion of what is present. It does not say how much peptide is in the vial. That is a separate measurement, and if it is not on the page you can ask for it.

DevManchester, UK

The wavelength is the bit people skip and it is the bit that tells you whether two documents are even comparable. Thank you for putting it in order like this.

FabianBasel, CH

Mine arrived in the box rather than after an email, which I had assumed was ordinary until I ordered somewhere that did not do it. It is not ordinary.

NilsUppsala, SE

Worth adding for anybody reading: two laboratories running different gradients can resolve a close-eluting impurity differently and both be right. A few tenths between an independent figure and a published one is a methods fact rather than a finding.

AnnaAthens, GR

I asked for the manufacturing record quoting the lot code and it came back without a follow-up. I had built that request up into something much bigger than it was.

SunilFacilitatorBirmingham, UK

Adding this to the circle's standing resources, because it is the clearest walk through a certificate anybody here has written. One thing I will say in my own voice: none of this makes buying outside a prescription safe. It makes you better informed about one narrow question, and that is all it does.

Facilitator note — Sunil

Nothing in this thread is medical advice. Research-use-only material is not approved for use in a person, and a certificate does not change that.

Resources mentioned