Compositions containing a \u03b1-sulfofatty acid ester and a hydrotrope. In the purification method of the present invention, nucleic acids are separated from proteins found in the same biological sample by applying the sample to an electrophesis gel and subjecting the sample to electrophoresis under acid conditions to separate the nucleic acids from the proteins. The retirement unit may further include logic to calculate an event associated with an executed instruction if information associated with the executed instruction is stored in an on-demand portion of at least one of arrays. When the button is pushed downward, the two pins are guide to separated in opposite directions so that the connection member together with the connection piece can be removed from the positioning member.