SYSTEMATIC STUDY OF FIELD AND CONCENTRATION EFFECTS IN CAPILLARY ELECTROPHORESIS OF DNA IN POLYMER-SOLUTIONS

A systematic study of the separation of double-stranded DNA in hydroxy propylcellulose (HPC) with a molecular mass of 10(6) was undertaken, u sing a variety of concentrations (from 0.1 to 1%) and different electr ic fields (from 6 to 540 V/cm). The data show that at high polymer con centrations (greater than or equal to 0.4%) and low fields, the separa tion mechanism is similar to that occurring in gels. The results are i n good agreement with theoretical models, and in particular with a rec ently proposed theory for gels with a pore size smaller than the persi stence length of DNA. For more dilute solutions and high fields, howev er, the separation pattern cannot be explained by existing theories. T he existence of an original mechanism was confirmed by the direct obse rvation of the conformation of double-stranded DNA molecules in the po lymer solution by fluorescence videomicroscopy. Practical conclusions for the capillary electrophoretic separation of duplex DNA are drawn.