One option is to use a kit from ZYMO Research, which is called "DNA clean and concentratior" kit. Zymo have several options of this product and it works really good. I work with 70bp fragments which undergo lot of enzymatic processing. I have been able to get ~70% recovery of 200 ng DNA in to 10 ul volume using this kit. My target experiments are sensitive like NGS, couple of very nasty enzymes treatments etc but it works great,..

One option is to use a kit from ZYMO Research, which is called "DNA clean and concentratior" kit. Zymo have several options of this product and it works really good. I work with 70bp fragments which undergo lot of enzymatic processing. I have been able to get ~70% recovery of 200 ng DNA in to 10 ul volume using this kit. My target experiments are sensitive like NGS, couple of very nasty enzymes treatments etc but it works great,..

Try Microcon or Amicon filters from millipore. We use them all the time and recovery is actually quite good.

Jesper

If you frequently need to concentrate samples it might be a good idea to spend money on a SpeedVac or any other vacuum concentrator. We usually get the best results with those instruments