Wash buffer

Dr. Demetriou thanks you for your answer and asks you to consider the reagents in the wash buffers and re-think your answer. You report that there are normally two wash buffers used. You go on to explain that the first wash buffer contains a low concentration of chaotropic salts and ethanol, while the second wash buffer contains only ethanol. Dr Demetriou commends you on your excellent response and goes on to explain that the first wash buffer helps to remove proteins, salts, and other contaminants from the DNA bound to the silica membrane without eluting the DNA, while the second wash buffer further cleans the DNA by removing any remaining contaminants, such as salts and residual proteins, ensuring that the final DNA preparation is pure. You thank Dr. Demetriou for helping you clarify this and proceed to reconsider your response.