Shelf life of buffers? (unopened) - (Sep/01/2009 )
First of all, all buffers mentioned in this post are "unopened" since preparation.
Recently my supervisor told me to throw away all media/buffers that are at least eight months old because they are considered "expired." Now, I understand that certain media such as DMEM, RPMI, etc. would expire after such long time, but buffers like PBS, 10XPBS, 1xTE, 10xTE, 20xSSPE, Tris/Saline, M9 Salts, 50XTAE, 20XSSC, 10XTBS, 10XTBE, and Tris-HCl? I know of people who use those buffers that are more than 3 years or older, and they have had no problem whatsoever. I tried to convince my boss that the shelf-life of unopened buffers is 1 year at least, but she wouldn't listen. The reason? Someone of more authority who is very "fresh obsessed" apparently mentioned to her that any buffer made last year (2008) or earlier is as good as garbage.
Anyway, it looks like I have no other choice but to toss the old buffers. But before I do that, could someone tell me an approximate shelf life of the following unopened buffers/media?
1) PBS-, PBS+, 10XPBS (filter-sterilized)
2) 20XSSPE, M9 Salts, 1XTE, 10XTE, 5M NaCl, 0.5M NaHPO4 (autoclaved)
3) 50XTAE, 20XSSC, 10XTBS, 10XTBE (autoclaved)
4) Denaturation buffer, neutralization buffer (autoclaved)
5) Tris-HCl (various pH values and molarities) (autocalved)
6) 0.5M EDTA (autoclaved)
7) LB Broth, 2X YT Broth, 5X LB Broth, SOC, SOB, TB (autoclaved)
In addition, is it feasible to re-autoclave/re-filter the "expired" buffers and put on a new date so they wouldn't be treated as garbage by some people? I mean, throwing away all that is so wasteful, especially since the buffers have not become cloudy or showed any other signs of degradation such as pH changes.
Thanks for your help.
Personally, I would just toss them if she so desires -- making fresh buffers is not that big a deal.
However, if you want to get an idea of how long such things are good for, I would look them up on commercial websites that sell them as prepared buffers (like Sigma, Fisher, etc.) and see what they use for an expiration date.