Domestic fridge temperature mapping: a cheap experiment — what changed since — setting out what I have, and where I think it stops being reliable.
What changes if the standard account of Domestic fridge temperature mapping is wrong? I ask because I have been treating it as settled and I noticed this week that I could not say why.
Working through the consequences rather than the evidence, since others here are better placed on the evidence.
A temperature indicator that has tripped tells you a threshold was crossed. It does not tell you for how long, and duration is most of what determines whether anything happened.
The literature is thinner on this than the confidence in the thread implies.
The arithmetic in post #3 is right; the assumption feeding it is the part to check.
Photographing the parcel on arrival, before opening, takes ten seconds and is the difference between a report and a recollection.
If this contradicts something upthread, the upthread version may well be the better one.
Genuine question rather than a rhetorical one: has anyone here actually observed Domestic fridge temperature mapping, as opposed to read about it? The thread is long and I cannot tell.
Domestic refrigeration: most lyophilised peptides are stored at 2–8 °C (35–46 °F). That is standard refrigerator temperature. Check your refrigerator's actual temperature; some are warmer than the label.
Genuinely open to being wrong about this one.
Everything in post #3 holds. The case it does not cover is the one I have.
The honest summary: pack quality is visible, transit history is not, and only the second determines what happened to the material.
Narrowing post #7, because the general version has more than one answer.
The version of Domestic fridge temperature mapping that circulates here is a simplification of a simplification. It is not wrong, but it has lost the conditions under which it holds, and those conditions are where the interesting cases live.
That is consistent with mine, for whatever one more account is worth.
This follows post #7 rather than contradicting it.
A phase-change pack holds a defined temperature while it changes state and then behaves like anything else. A gel pack starts cold and warms continuously. They are different tools for different transit lengths.
Post #8 is the version of this I will quote in future. One addition.
Shipping container and cold packs: reputable suppliers use insulated containers with cold packs designed to arrive cool. Checking on arrival that cold packs are still cold is a sign the chain was maintained.
The practical version of Domestic fridge temperature mapping is three sentences long. The rigorous version is three pages and reaches the same conclusion with the conditions attached.
No disagreement from me. Posting only so the question does not look ignored.
Post #15 put the caveat in the right place and I want to underline it.
Lyophilised material is far more tolerant of a warm transit than a solution would be, which is why suppliers ship dry and why an excursion is not automatically a loss.
The arithmetic in post #16 is right; the assumption feeding it is the part to check.
Repacking cold material into a domestic refrigerator promptly on arrival is the one step that is entirely within your control and the one most often delayed.
Flagging that the sources on this are thinner than the confidence in the thread suggests.
Having read the whole Domestic fridge temperature mapping thread before replying: the question in the first post has not actually been answered yet, and three of us have answered a nearby one instead.
The thing about Domestic fridge temperature mapping that took me longest to accept is that a plausible mechanism is not evidence of an effect. It is a reason to look, not a result.
Temperature loggers in the parcel exist and are occasionally used for high-value shipments. They are the only thing that turns an argument about transit into a record.
Reading it again, the caveat matters more than the finding.
Before the thread moves on from Domestic fridge temperature mapping — what is the sample size behind the claim? I am not being difficult; I have seen the same figure quoted from an n of four and from an n of four hundred.
Post #19 describes the usual case. This is about the unusual one.
Two things can be true about Domestic fridge temperature mapping at once: the mechanism is plausible and the evidence for the size of the effect is thin. Most of the argument here is people defending the first against attacks on the second.
Freeze-thaw: some peptides tolerate freezing; others do not. Check your compound's labelling. Generally, repeated freeze-thaw is worse than single freeze-thaw.
Practical note on Domestic fridge temperature mapping: 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.
The arithmetic in post #27 is right; the assumption feeding it is the part to check.
Temperature excursions: brief excursions above 8 °C are tolerable for most compounds. Hours to a day at room temperature is usually acceptable. Days to weeks at room temperature risks degradation.
Answering the Domestic fridge temperature mapping question as asked, then the question I think is meant. As asked: yes, with the qualification below. As meant: it depends on how the first measurement was taken.
Taking post #27 at face value and following it one step further.
On Domestic fridge temperature mapping: the maintained page in the documentation commons covers the general case with citations and a review date, which is more reliable than any reply here including this one.