For plasmids, we recommend the use of commercially available
plasmid mini scale preparation kits employing spin columns. From
our experience, repeating the washing step will improve the quality
of the DNA and therefore improve the sequencing results. Please do
not send DNA prepared with alkaline lysis methods or with the
boiling method (Holmes and Quigley, 1981) without column
purification. For PCR products please use commercially available
PCR purification spin column kits.