EFFECTS OF SAMPLE MATRIX AND INJECTION PLUG ON DSDNA MIGRATION IN CAPILLARY GEL-ELECTROPHORESIS

Reproducible DNA migration times are required for accurate basepair as signment in restriction fragment mapping and polymerase chain reaction product identification. Our data shows DNA migration time shifts with changes in sample ionic strength. Secondly, loss of resolution with r eplaceable polyacrylamide gels was observed when increasing the. lengt h of the sample plug with pressure injection. An easy way to correct f or the migration time shifts is to incorporate an internal DNA standar d directly into the separation process by consecutively injecting the DNA sample and the DNA standard. This allows for compensation of any p ossible migration time variation caused by high ionic strength sample matrices. Also high-resolution separations can be maintained with larg e injection volumes (long injection plug) by using consecutive injecti ons of 0.1 M Tris-acetate buffer and the DNA sample.