Why does my gel have streaks instead of bands? - (Apr/14/2014 )

We make hand-made gels in my lab and they weren't a problem until a couple weeks ago. We weren't changing anything and all of our solution were freshly made.

For sample preparation, we add the loading dye to the samples and then boil them at 100C for about 10 minutes.

The most recent gel looks like this... Any suggestions as to what could be going wrong?

are the samples the same as in the past?

could be salt in the samples, overboiling, incomplete solubilization.

the sds may be decomposing. you prepared fresh reagents, did you use a fresh lot of sds?

what about acrylamide? what grade do you use? how do you prepare it? how old is the lot?

check to make sure all of your solutions have been prepared properly.

(my main guess is salt)

Do you make your acrylamide mix or is it premade? If it's premade, what temp do you store it at?

Also have you always boiled samples for 10 min? I've always opted for 5 minutes, as does everyone in my department.