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antibiotics at room temperature


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10 replies to this topic

#1 subha

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Posted 13 March 2009 - 10:57 AM

Hello all,
I did a stupid mistake, and realized it later. We usually store Ampicillin and Kanamycin antibiotic solutions (50mg/ml) at 20 degree C. But somehow after using those antibiotics , I left them at room temperature(25/26 degree C) for 2/3 days . After realizing the mistake I quickly put them back in -20 degreeC. Will they be fine , or I have to prepare new ones?

#2 lotus

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Posted 13 March 2009 - 11:28 AM

toss them and prepare new ones. They might still retain some antibiotic activity, but you can't tell how much.

#3 GeorgeWolff

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Posted 13 March 2009 - 01:56 PM

agree with lotus - for 2 reasons. One, it's sloppy science and two they may be contaminaed.

#4 molgen

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Posted 15 March 2009 - 02:35 AM

I agree with lotus andGeorgeWolff - for one more reson: They're not that expensive that it pays to take the chance to go one working with them.

#5 bob1

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Posted 15 March 2009 - 03:28 PM

I wouldn't trust the amp, but the Kan is stable for 5 days at 37 deg C and for long term storage at 2-8 deg C, according to the product sheet.

#6 GeorgeWolff

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Posted 16 March 2009 - 12:27 PM

Wouldn't consider kanamycin or any antibiotic "stable" in context of a nonsterile solution.

#7 bob1

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Posted 16 March 2009 - 03:46 PM

OP says nothing about contaminated, just says that they left the antibiotics on the bench overnight. I was assuming standard sterile practice.

#8 perneseblue

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Posted 16 March 2009 - 06:00 PM

Personally, unless this antibiotic is being used for titration purposes, I would still use the antibiotic.
Certainly there is some degradation. But does it matter in this situation? The amount of ampicilin used in a selection plate for cloning purposes varies from 100ug/ml to 25ug/ml. My lab uses 25ug/ml but I have seen labs use 100ug/ml

So, if you assume degradation of the antibiotic I would use 50ug/ml or 100ug/ml which would give me more than enough antibiotic for selection.

I feel it is such a waste to dump a vial of antibiotic stock solution, when the finally concentration of the antibiotic isn't important.
May your PCR products be long, your protocols short and your boss on holiday

#9 Paraboxa

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Posted 17 March 2009 - 01:59 AM

I think I'd still use the antibiotics. Note down in your lab book what happened and obviously you'll record which batch of antibiotic you use so that you can trace dodgy results.

Do you run a test plate when you make up your antibiotics? You could run a plate to test the efficiency of your experimental dose. (Not that I ever did a test plate on each antibiotic batch I made up. Does anyone else?).

#10 GeorgeWolff

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Posted 17 March 2009 - 03:00 AM

At minimum, make sure the solution has not become contaminated.

#11 HomeBrew

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Posted 17 March 2009 - 05:35 PM

If contamination is a suspected issue, push the solution through a 0.22 um syringe top filter.

I personally would toss the antibiotic and make a fresh stock because most of the time, the antibiotic comes into play after I've performed many laborious steps leading up to selection, and I'd rather waste some antibiotic then all that labor.




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