stability of ampicillin n kanamycin plates. - (Sep/21/2007 )

can anyone tell me for how long ampicillin, kanamycin, spectinomycin, streptomycin and hygromycin are stable in LB-agar plates? what is the optimal temperature of their storage?

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Store them at 4ºC.

I usually seal them and kepp them stored for weeks (sometimes a couple of months...).
I've read that some people only trust them if they're stored for one or two weeks or so.

Different antibiotics have different stability, but I really don't know which are more and less stable... You can always ask the manufactor for some info.

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well... i would not go more than 2 monthes.
Keep them inverted in bag at 4° to limit evaporation and degradation of antibiotics.

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there is decline of antibiotics efficacy over the time (weeks);

after some weeks it is difficult to estimate the effective concentration; better use the plates freshly poured, or store plates without antibiotics and add them freshly before use; in this case you should use a fixed volume (f.i 20 ml of agar) to calculate what you have to add

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thank you friends for suggestions...

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