Revisiting: Mean kinetic temperature explained without the mathematics posts 31–60

Temperature excursions in transit are common and are not all equal. A few hours warm is a different event from three days warm, and neither is visible in the vial on arrival.

That holds for the case as described. Change the assumptions and it may not.

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.

That is the version I use. It may not be the version that is correct.

Source for the Mean kinetic temperature figure, since it was asked for. It is in the discussion rather than the abstract, which is why the version circulating is stronger than the paper is.

Reading the surrounding paragraph is worth the two minutes. The authors are more careful than their summarisers.

I had read the opposite somewhere and cannot now find where, which tells me something.

This follows post #32 rather than contradicting it.

Practical note on Mean kinetic temperature: write down what you expect before you look. The number of times I have found what I went looking for is higher than chance would allow.

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

That is one dataset and I would not build a rule on it.

I disagree with the framing of Mean kinetic temperature above, and I think it is a substantive disagreement rather than a terminological one. Setting out why, so it can be checked.

The reasoning depends on an assumption that is doing a lot of work and is never stated. If the assumption holds, the conclusion follows. I do not think it holds generally.

Mean kinetic temperature is one of those subjects where the general answer and the answer for a specific case diverge, and the thread will go in circles until someone says which one is being asked for.

The arithmetic in post #36 is right; the assumption feeding it is the part to check.

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

Answering the question post #38 raises rather than the one it answers.

The most useful thing anyone has posted about Mean kinetic temperature in this category was a table of what had been measured and by whom. That is what I would want again.

The honest summary: keep it dry until you need it, keep it cold once it is not, keep it dark, do not cycle the temperature, and treat any period at room temperature as spent whether or not anything visible happened.

Temperature excursions: if a vial sat at room temperature for a time, the question is whether the excursion was long enough to cause damage. Hours at room temperature is usually low risk. Days to weeks raises the risk. If you are unsure, contacting the supplier is more informative than guessing.

The disagreement above is smaller than it looks once the terms are fixed.

I had written a reply contradicting post #39 and deleted it. Here is what survived.

The question underneath Mean kinetic temperature is usually "how would I tell?" rather than "what is true?", and that one has a method attached to it.

Write down what you would expect to see under each hypothesis before you collect anything. If they predict the same observation, collecting it will not help.