Ampicillin kills my hands! - (Jun/25/2012 )

Hello all,
I am a Lab Tech at UF in Gainesville, FL. I study plant pathogens and regularly use Ampicillin aliquots in media.
My question is: Whats the easiest way to get the Ampicillin to pass through the 0.22um filter? I am using 10g of Amp in 20ml of sterile h20.
Everytime I have to make Amp, my hands hurt for days after because I have to force the soultion through the filter and it gives me a lot of resistance.
I read something about using ethanol to make it more soluble or easier to pass through the filter, but was unable to verfiy this. Any and all help is much appreciated.
Thanks in advance
Jackson

you have a final concentration of 500 mg/mL which sounds quite high for me I usually make a 100mg/ml stock and the ampicillin dissolves slowly in water, so probably you are above the soloubility of ampicillin? so not all of the ampicillin dissolves and your filter cloggs?

If not: can you filter it twice, e.g. first a 2µm filter and then the 0.22; or use an electrical filtration system.....

i talked with my PI to day about the concentration and I have now changed it to 100mg/ml stock and just doubled the aliquots to give me a final concentration of 200mg/ml. The 0.22um filter is what gives me the resistance. not nearly as bad now with the 100mg/ml stock though. thanks for the help

You may find it convenient to dissolve the ampicillin in 50% ethanol at 100 mg/ml, which allows it to be stored at -20C while still liquid. This makes it far easier to add to culture medium while keeping it cold. The ethanol also keeps it sterile. I would also be using carbenicillin rather than ampicillin, to avoid the breakdown at 37C on longer incubations.

forgot: which type of filter do you use? check if you accidentially use a hydrophobic filter material - because this could be the reason that you need much force to filter your solution.....