I have come up with what I thought was a clever idea: Store the agarose gels I pour, and only cut as many lanes as I need to run later, minimizing wasted agarose (and wasted effort/time) when I need to make many electrophereses using a small number of lanes.
I realized that over time, the EtBr would diffuse out of my gel into the buffer that the gels are kept in. Since I add 2 µl of EtBr to 50 ml gel, and the gels were kept in 400 ml TAE buffer, I added 16 µl EtBr to the buffer, reasoning that now concentrations are equal and no net diffusion will take place.
However, after several weeks, I noticed that the EtBr signal from the gel is severely weakened. What can I do to fix this? I can see the following options:
- Use higher concentration of EtBr in the buffer (how much?)
- Change buffer weekly, adding fresh EtBr every time
- Cover the transparent container with aluminum foil to prevent hypothetical photobleaching
Which one is most likely to solve my problem? Should I just give up, and throw away gels that are older than a day or two (I want to avoid this option, because of the record keeping needed to track when the gel was last made)?