lotus, on Jan 20 2010, 03:48 PM, said:
I wanted to make LB-Amp plates today, so I made 500 ml of LB-agar and sent it to autoclave- our university has a central autoclaving facility manned by two employees. When I collected it, I cooled it down, added 500 ul of my 100 mg/ml stock amp and started pouring my plates. Midway through, I realized that the I was going to run out of LB-agar and the volume in the flask was very low. I think some lb-agar must have boiled over and been lost during autoclaving. I poured 16 plates in total, but the problem now is that I added 500 ul ampicillin, so each plate will have a lot more ampicillin than 100 mg/ml. Should I just discard the plates or are they usable?
I think you'll be fine. We use 200 ug/ml in our LB-Amp plates. Your concentration shouldn't be higher than that... assuming you poured 25 ml plates and got 16, that's 400 ml to begin with, so the concentration of Amp will be about 125 ug/ml instead of 100 ug/ml. No biggie.