Nonaqueous capillary electrophoresis.

This paper reports an investigation of performing capillary electrophoresis (CE) in formamide. Formamide has a higher dielectric constant than water and can solubilize many supporting electrolytes. It is commonly used in mixtures with water in electrophoretic buffers. It has higher viscosity than water and hence ions exhibit lower mobilities in formamide. As a result, higher electrolyte concentrations and electric field strengths can be used. The linearity between current and the applied voltage is better in formamide. The implications of using larger ionic strength and higher electric field strength on efficiency and analysis times in CE are demonstrated in this paper. Higher efficiencies and shorter analysis times were obtained using formamide, under similar conditions, as compared with aqueous media. Other possible implications of using nonaqueous media on Joule heating, extending the workable range of the capillary diameter, sample sizes, and detectability, are discussed.