Second pass at: Adsorptive losses at low concentration, and why dilute solutions are fragile posts 61–88

Published stability data covers a specific formulation at a specific concentration in a specific container. A home-reconstituted preparation matches none of those, and that caveat is the whole of the honest answer.

That is what I would do. It may not be what is correct.

I would call the community position on Adsorptive losses likely rather than established, and I would be comfortable defending that hedge.

I read post #74 twice before replying, because I had assumed the opposite.

What I can speak to on Adsorptive losses is narrow, so I will keep it narrow rather than generalising from it. Beyond that boundary I do not know.

Visible particulate is a strong signal in the other direction: it is a reason to stop and ask rather than to filter and proceed.

I have changed my mind on this once already, so take it as current rather than settled.

Answering the question post #77 raises rather than the one it answers.

If someone has run Adsorptive losses properly I would rather read that than my own reconstruction of it. Posting mine only because the thread has gone quiet.

The arithmetic in post #77 is right; the assumption feeding it is the part to check.

Marking my uncertainty on Adsorptive losses explicitly. I am confident about the direction, much less confident about the size, and not confident at all that it generalises past the case in the first post.

What is reasonably well supported: refrigeration slows degradation, repeated warming and cooling is worse than either state alone, light exposure is worth avoiding, and adsorptive losses matter more in dilute solutions.

The honest answer is that it depends, and here is what it depends on.

Adsorption to container surfaces removes peptide from solution without changing how the solution looks. In dilute preparations that loss can be a meaningful proportion, and it is invisible.

This follows post #82 rather than contradicting it.

Checked the Adsorptive losses claim against the primary source this morning. It survives, with a narrower scope than the version quoted here. Posting the narrower scope.

Worth separating two things that post #80 runs together.

Clarity is a weak test. A solution can lose a significant fraction of its active content to degradation or adsorption while remaining perfectly clear.

Dating prepared solutions: write the date reconstitution on the vial in permanent marker. If you later need to know whether it has been sitting for weeks or days, the date tells you. Guessing on this is where errors accumulate.

Adding the caveat now so it does not have to be extracted later.

Summarising the Adsorptive losses thread so far, since it is long and the answer is buried: the first reply has the method, the fourth has the correction to it, and the rest is people agreeing at length.

On post #84 — agreed on the reasoning, with one qualification.

Published stability data covers a specific formulation at a specific concentration in a specific container. A home-reconstituted preparation matches none of those, and that caveat is the whole of the honest answer.