Hi, is it DNA from PCR, for cloning?? I usualy use promega kit, and becarfull with the date, if the kit is to old, you can loose a lot of DNA.

Try low melting point agarose. Pre-cool everything you use including tank and buffer. load the pre-cooled gel out side colde cabinet and transfer again for final run inside 4 deg C cabinet (or fridge). It definitely works. Discuss again If does not help.

Instead of using 50ul of elution buffer, you can use a lower volume like 30ul, the concentration will increase

Check the size of your DNA product. If size is =50 or

First of all, 10-20 ng/ul is sufficient for most applications unless of cause you are trying to purify high molecular weight DNA.

If the size of the DNA is < 80 nt, try increasing the amount of binding buffer added. Remember to add a second centrifugation step after performing the wash to completely remove all the ethanol. Elute DNA with pre-warmed elution buffer.

As an alternative, you could try electroelution.

Jesper

In Qiagen gel extraction kit protocol you have to remember following things:

1) Do not use more than 400mg 1% agarose gel on single column.

2) After gel digest adjust pH by acetate buffer

3) Add 0.9 volume of isopropanol with gel (Qiagen recomends 1 volume)

4) Give extra spin before and after PE buffer.

5) Elute DNA with pre-warmed elution buffer (also suggested by others)

DNA, RNA and Protein purification kit from Machery-Nagel (www.mn-net.com) works well. I use it to gel purify DNA of up to 2kb with good yield (PCR product or digested plasmid). For PCR product, i recommend to use a 50ul reaction. Before elution, you may pre-warm your elution buffer at 65-70 degreC before loading onto the column and after loading the elution buffer wait 5 min before spin. Also, by eluting your DNA 2-3 times will increase your yield. To improve the concentration of your DNA, reduce the volume of the elution buffer or water.