Separation of Supercoiled and Open Circular Forms of Plasmid DNA by Novel Analytical CIM Monolithic Columns

Anion-exchange chromatography is fundamental in downstream processing of plasmids both as a process and analytical technique. CIM anion-exchange monolithic columns have already been successfully used for the industrial scale purification of pharmaceutical grade small plasmid DNA [1].

In this work we report about the use of the newly developed monolithic analytical column intended for plasmid DNA determination in terms of its analytical performance. Higher degree of sensitivity, precision and accuracy is necessary in order to determine the quality of clinical grade DNA intended for therapeutic use. Plasmids purified from Escherichia coli fermentation exist predominantly in the supercoiled form (SC) the other two topoisomers present in the final product are mostly the open circular (OC) and linear forms [2]. Different chromatographic conditions were tested and the separation was optimized in terms of buffer and pH selection as well as in terms of gradient slope and column length. The results were compared to the results obtained with established analytical methods.