Domestic fridge temperature mapping: a cheap experiment — what changed since posts 121–150
This is a continuation of a long topic, addressed by post number rather than by page. Start at post 1.
Post #118 describes the usual case. This is about the unusual one.
Reconstituted solutions: once reconstituted, solutions are less stable than lyophilised powder. Refrigerate prepared solutions immediately after preparation. Most stability claims assume refrigeration.
That is a cleaner way of putting what I was circling around.
Domestic fridge temperature mapping has a well-known answer and a correct answer, and the interesting work is establishing that they are the same. Nobody has done that here yet.
The interaction between cold chain and the storage question is that a warm transit spends part of the material's stability budget before it reaches you, and the budget is not visible.
Confirming post #124 from a second method, which matters more than confirming it from a second person.
A parcel sitting in a vehicle or a depot in a hot month is the excursion that matters and the one nobody sees. Delivery timing is part of the cold chain.
I had written a reply contradicting post #126 and deleted it. Here is what survived.
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.
If anyone can point at the primary source I would be grateful.
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.
I have written this out at length because the short version keeps being misread.
Reading back through the Domestic fridge temperature mapping threads from last year, the same three questions come up every time and only one of them has ever been answered properly. That seems like a documentation gap rather than a knowledge gap.
I read post #129 twice before replying, because I had assumed the opposite.
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.
I would want a second opinion before relying on that.
Collapsed as off-topic by two members at trust level 3 or above
Post #133 answers the question as asked. The question underneath it is different.
My experience of Domestic fridge temperature mapping contradicts the reply above. I am posting it as a data point rather than as a refutation, because one person's experience is exactly that.
Coming back to post #133, because the follow-up matters more than the original answer.
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.
This is where my knowledge stops and I would rather mark the edge than blur it.
Assessing an excursion: if a package sat at room temperature for a time, visual inspection (cloudiness, discoloration, particles) can alert you to problems. Not visible does not mean not damaged, but visible problems are a reason to contact the supplier.
Anyone with a larger sample, please post it.
Collapsed as off-topic by two members at trust level 3 or above
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.
I have seen it go both ways, which is why I hedge.
Building on post #137 rather than restating it.
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 short answer was in the first line; everything after is the working.
Post #140 and I disagree about the size of the effect, not about the direction.
I would put moderate confidence on the mainstream reading of Domestic fridge temperature mapping and no more. That is not scepticism for its own sake; it is where the sourcing actually stops.
Building on post #142 rather than restating it.
Domestic fridge temperature mapping is well covered in the tag pages, and the older discussions are better than the recent ones because they were argued out properly. Worth twenty minutes before adding to this one.
Post #145 put the caveat in the right place and I want to underline it.
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.
That distinction has done more work for me than anything else in this category.
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.
The reasoning is more useful than the number, which is why I have shown it.
Right — I had this wrong and I am glad to have read it before it mattered.