I have a delivery of Coaguchek test strips arriving today via USPS. It was -14 F this morning and expected high of no more than +8 F. Does anyone know if there is a minimum temp specified for these strips? I know the documentation says "do not freeze" in relation to storage. Any risk to quality if they are in these temps for a brief period of time?
Coagucheck Test Strip Minimum Temperature Threshold
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pellicle
Professional Dingbat, Guru and Merkintologist
there is a minimum temp required to do a test and the "do not freeze" gives you a minimum temp for storage.
The Coaguchek will not work outside particular temperatures, which in the manual are given as:
15C to 32C (59 - 90F).
were they in any sort of packaging? Mine commonly come in a cardboard box with an amount of fill packaing; this would act as an insulator. Given that they were delivered by UPS they wouldn't be freezing in the possession of UPS, if they were not left outside for hours then they wouldn't have frozen.
However I believe that the reagents will not be damaged by a brief freeze, and that the issue with freezing will be eventual water migration and sublimation:
Sublimation has also been used as a generic term to describe a solid-to-gas transition (sublimation) followed by a gas-to-solid transition (deposition)
and that unlike (say) lettuce there are no cell membranes to be ruptured (which is why lettuce goes limp when frozen) by the ice crystal formation. There will be water held in the chemistry on the strips but that's rather different.
Make sure you leave the bottle to reach room temp before opening it. Even when storing in the fridge (which I do in summer because 40C is a daily thing for much of the year and the house gets to 4C in winter (don't ask)).
Final test is to do a test and if its within bounds it'll be fine. This is the prime test. Myself I used to have a habit of doing a "hand over" test on new strips (testing twice on the same sitting with the last of the old and the first of the new), but I haven't done that for years now (it was always the same number).
If you want to provide more information about my questions we could discuss it further, hope this helps.
pellicle
Professional Dingbat, Guru and Merkintologist
it may have got to freezing, but I suggest only briefly
worth considering in North America (including Canada) is that temps often include "wind chill factor" which is pretty meaningless IMO. I've had a Canadian tell me how it was -8C and I said "well my water isn't freezing, which it would if it was actually -8C"
Water in the bottle isn't going to freeze when its just windy out, it needs actually freezing temperatures
After looking at the shipping details and timeline, I think the strips are fine. Both external and internal boxes were well sealed and shipped from Arizona which was warm and dry, so unlikely that any moisture got in there . Temp here was +7F (-14C) actual air temp - not wind chill which would feel a bit colder with the light breeze we had.
