I believe using alkaline lysis method to extract plasmid DNA from E. coli cells is a pretty mature method. To do it, I followed the popular protocol by adding 0.2 M NaOH and 1% SDS to DI water. Then I found the pH of this lysis buffer is about 13.5, which is high enough to denature DNA. So I searched online and people recommended using lysis buffer of pH = 12. But I am not sure if this recommended pH=12 is the pH for the pure lysis buffer, or for the mixture of resuspension buffer + lysis buffer after adding lysis buffer to the resuspended cell suspension? Anyone can help?