Not your typical science blog, but an 'open science' research blog. Watch me fumbling my way towards understanding how and why bacteria take up DNA, and getting distracted by other cool questions.
Make sure your APS hasn't gone to hell either.
I make the APS (ammonium persulfate) fresh, mainly because that's what I was taught and I don't know enough about the chemistry to decide how long it would keep at room temperature or frozen.
LOL. This happened to me in the Summer.
@Rosie: 10% APS can hang out for up to three months at 4 degrees. But dry APS can go off too. Keep it in a dessicator if you don't already - once it starts looking wet, it's done.
Ah yes, casting gels for the first time after years. I tried that recently, using a recipe my grad student gave me. I was too daft to realize that he uses a far more dilute APS solution than I always make. My gels set the moment I tried to pour them. Luckily it was late, so only about ten people saw me...
I make 10 % APS solutions (10 ml) and make 1 ml aliquotes and store at -20C. Keep the thawed tube at 4C till it get used up. This works great for me. What is the recipe for your gel? I use the Sambrook recipe and it works fine.
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