Gel Extraction of DNA - (Aug/02/2005 )
I tried to elute the DNA from the 0.8% gel using Qiagen Gel extraction columns. I used 30ul MilliQ water to elute the DNA. But after some time( about 1 hr) I observed a thick gel like substance in the microfuge tube instead if water with DNA!!! What could have gone wrong? Is it agarose that passed through the membrane or something else?
Thanx in advance.
I use that kit quite often, but never come accross this problem before. You should make sure the gel is dissolved when you heat it at 50oC. And I do not think it is possible for the gel filter through the membrane. I elute the DNA by MILIQ water as well.
It is likely to be agarose. It is possible that the membrane was faulty or damaged and it let the agarose through.
Troubleshooting help for automated DNA sequencing
I have done this a lot of times but have never had this problem. Try putting your sample at 50 degrees and see if it melts. If it does you will be sure that somehow the agarose got into your sample.
You can also include a wash step to remove traces of agarose with the first buffer (the yellow one - don't recall the name of it offhand).
Thank u all for the replies. Indeed it seems like agarose which got melted after incubation for few seconds at 55C.