I've been using a protocol to extract DNA from blood parasite in whole blood using a lysis buffer with TrisHCl, EDTA, SDS and Triton X-100, and a proteinaseK step.
The lysed material is then treated with a phenol:chloroform extraction and when spun I am getting what I can best describe is like a layer of soap between the organic and very tiny aqueous phase.
This protocol had been working just fine and suddenly all samples get this "soap" layer.
I have remade solutions, obtained new proteinase K and new phe:chl.
In addition I have pH'd everything and nothing appears abnormal.
any suggestions would be gratefully received!!