solution expiration date

[yanyan]

Hi there,
I have seen people setting up the expiration date on solutions containing a ratio of HPLC grade organic solvent and water, let's say acetonitrile/water 50:50 or higher ratio on organic, etc., at a range of 2 weeks to 3 months from lab to lab. I would like to extend the expiration date to more than two weeks, however I need to have supporting document for it since I am in a FDA regulated environment. Could anyone know any information/literature I can use for? I appreciate any help.

[bisnettrj2]

This topic has been discussed ad nauseam. See the threads below. Good luck - there's not a lot of consenesus, from what I briefly skimmed.

viewtopic.php?t=5993&highlight=expiration

viewtopic.php?t=3070&highlight=expiration+date

viewtopic.php?t=1078&highlight=expiration+date

viewtopic.php?t=11561&highlight=expiration

viewtopic.php?t=7487&highlight=expiration

viewtopic.php?t=6511&highlight=expiration

[Blazer]

I am not sure you're going to find any supporting documentation to backup whatever expiration period upon which you decide. I do not believe there are any official regulations on the topic, hence why you will find such varied answers when you ask that question. The only agreement I have seen from lab to lab is that an aqueous solution has a shorter expiration period than an aqueous/organic mixture. Typically these have are given a shelf life of one to two weeks, depending on if any studies have been performed to support the date given.

[DR]

As long as your expiration dates strike the particular FDA person you're dealing with at the moment as being in the range of all things "reasonable", their concern will be much more highly focused on:
1) Do your SOPs specify a means for coming up with an expiration date? (these means can be arbitrary or they can be based on research findings and experience)
2) Does your lab strictly adhere to the SOP?

[yanyan]

bisnettrj2,

Thank you very much for the links. I have read them and understood that people had been struggling to find solid evidence on determination of solution expiration date.

DR,

1) No
2) Yes.

To all who interested in the topic,

I feel lucky today that I have found an article in which there are 35 chemical solutions, acids, bases... elent mixtures been studied for their stabilities. They have concluded that 0.1N and 1N HCl are stable for over 6 months, ACN/H2O 20:80 to 90:10 are stable for 1 month when they stored properly. The article name is "Determination of the Expiration Date of Chemical Solutions", published by Springer. Here is the link: http://www.springerlink.com/content/5vh0e7c6qky1hl7x/. I believe this article can be used as a supporting document to set our solution expiration dates accordingly to meet the regulatory requirement.

Have a nice day!

[Alex Buske]

The article name is "Determination of the Expiration Date of Chemical Solutions", published by Springer.

I am really impressed: 2 M ammonium acetate, 0.03 M diammonium hydrogen phosphate, sodium dihydrogen phosphate (0.05 and
0.1 M), sodium chloride (5 ppm and 0.1 M) and sulphate (10 ppm) being stable for at least 5 months. I would have expected any kind of biological contamination. That wasn't tested.
acetonitrile/ water (20/80 and 90/10) only one month, as the acceptance criteria was +-2% relative, so its 9.8-10.2% water absolute. Usually robustness tests in HPLC validation include +-1-2% absolute change in composition, based on pump specs.

So the main risk in buffer solutions wasn't investigated and for HPLC eluents strange acceptance criteria were apllied.
BTW: it's published in: Accreditation and Quality Assurance: Journal for Quality, Comparability and Reliability in Chemical Measurement

[DR]

So, if you want to
1) include caveats about "any sign of biological infestation (flocculance, turbidity or growth)" and
2) include a table of what sorts of solutions go bad when and
3) cite the article

you may offer sound rationale in a solution dating SOP.

Personally, if it were me updating such an SOP and 1 month is the shortest common time in the article, I'd use that and include the caveat about biological activity.