The capillary gel electrophoresis (CGE) is the only reliable tool to analyse different plasmid topologies. Our unique CGE technology allows determination and quantification of the proportion of the ccc form. CGE service can be ordered optionally for every plasmid production or independently for external DNA samples. It documents the degree of plasmid homogeneity – a parameter not only of practical interest for achieving optimum transfection results but also required from a pharmaceutical perspective. The main contaminant of kit-based plasmid DNA – bacterial chromosomal DNA – cannot be quantified by this method.