June 02, 2020, 11:38:19 AM
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Topic: Shelf life and Enviroment  (Read 467 times)

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Offline becchino

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Shelf life and Enviroment
« on: January 24, 2020, 10:20:29 AM »
With a view to energy saving and environmental protection, are there studies on the validity of the reagents even after their expired date?

Offline Enthalpy

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Re: Shelf life and Enviroment
« Reply #1 on: January 28, 2020, 10:18:44 AM »
Do chemists care about expiration dates at all? Except in radiochemistry and possibly biochemistry.

For very specific reagents maybe, which are knowingly sensitive to time and whose transformation isn't patent?

Offline Corribus

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Re: Shelf life and Enviroment
« Reply #2 on: January 28, 2020, 11:29:41 AM »
Well, we care very much about decomposition of reagents. But generally we understand that printed "expiration dates" mean very little because storage conditions vary quite a bit and tolerance for decomposition products depends on specific use parameters. As a matter of course, in our lab we check the purity of starting materials routinely before they are used rather than relying on arbitrary expiration dates written on the bottles - which we are required to put there by our QA committee. Much to our annoyance, the expiration date is 5 years from the date of opening, which is ridiculous because this is the same requirement for sodium chloride and for highly photosensitive reagents. So, it means nothing.

Anyway, to the OP's question, this isn't something that is routinely studied or published because it's hard to extrapolate results from a controlled aging study to the highly uncontrolled conditions in real laboratories, or the many ways in which reagents are used. Studies on decomposition mechanisms are more common, which can be used to predict how reagents are likely to behave and can be used to guide best procedures for storage of potentially unstable chemicals. One exception I've noted is in the area of nanochemistry, as there are some highly regarded studies on the purity of reagents and control over nanomaterial properties. But these don't really relate to "expiration dates", given how meaningless these dates really are.
What men are poets who can speak of Jupiter if he were like a man, but if he is an immense spinning sphere of methane and ammonia must be silent?  - Richard P. Feynman

Offline Enthalpy

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Re: Shelf life and Enviroment
« Reply #3 on: January 29, 2020, 08:36:18 AM »
Somehow I had expected QA to be as pointless in chemistry as in electrical and mechanical engineering.

I guess Becchino expected operations like in food industry and was conducting some sort of economic study. But in a lab, chemists have better knowledge and means than an expiry date.

Offline Corribus

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Re: Shelf life and Enviroment
« Reply #4 on: January 29, 2020, 09:47:49 AM »
Somehow I had expected QA to be as pointless in chemistry as in electrical and mechanical engineering.
For the most part, it is. At least in a research lab.
What men are poets who can speak of Jupiter if he were like a man, but if he is an immense spinning sphere of methane and ammonia must be silent?  - Richard P. Feynman

Offline becchino

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Re: Shelf life and Enviroment
« Reply #5 on: February 06, 2020, 12:01:21 PM »
Thank you. I work in a pharma laboratory (GMP and FDA).
The expiration date of all solutions is a very critical (for standards, reagents, volumetric solutions, etc.).
Unfortunately (as you have noticed) the suppliers give untruthful dates.
I have thousands of reagents in use in the lab and honestly I can't do stability analysis on everyone.

Offline Enthalpy

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Re: Shelf life and Enviroment
« Reply #6 on: February 10, 2020, 12:05:44 PM »
Time is not what degrades most reagents, so an expiry date is just irrelevant. You suppliers indicate a date because someone (for instance their QA, or Law) instructed them to, so they just put some date and hoped nobody would care about.

If a compound is sensitive to light, CO2, oxygen, ozone... then the storing conditions decide, not the date. And even for some compounds that decompose slowly spontaneously, the storage temperature, the impurities added after opening the container, and so on, matter more than the duration.

So you're asking how to better apply an irrelevant metrics. The ideal answer would be to explain your QA that expiry date is irrelevant, but I understand it can be difficult, especially if your lab must justify itself before judges in the future.

Offline shchavel

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Re: Shelf life and Enviroment
« Reply #7 on: February 13, 2020, 02:56:37 PM »
Dear becchino! We had the same problem in our GMP QC lab. Auditors like to ask about solutions. We solve this problem by . solutions's shelf life validation.
1) Just classify our solutions to the groups (acids, alkali, inorganic solutions, ect.)
2) Choose the unstability one.
3) Prepare plenty of the solutions.
4) Test them regulary by assays.
5) Summary results.

It wasn't fast and easy, but it better than nothing.

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