Acrylamide gel elution buffer
10 mM magnesium acetate tetrahydrate
SDS improves the efficiency of recovery, most probably by blocking nonspecific adsorption of DNA to the walls of the tube. However, SDS is tenacious and difficult to remove from the eluted DNA, especially when purifying oligonucleotides on Sep-Pak columns. Perhaps the best advice is to use SDS only when attempting to recover very small amounts (<20 ng) of DNA >1 kb in size, where recovery is already inefficient and further losses may prejudice the success of the experiment. This is not usually the case when purifying synthetic oligonucleotides, which are always relatively small and usually available in abundance.
Other buffers may be substituted for acrylamide gel elution buffer. For example, if the DNA fragment is radiolabeled and is to be used as a hybridization probe, hybridization buffer can be substituted.
