N-METHYLFORMAMIDE AS A SEPARATION MEDIUM IN CAPILLARY ELECTROPHORESIS

The organic solvent N-methylformamide (NMF) has been used as a separat ion medium in capillary electrophoresis. The advantageous properties o f this compound are its high dielectric constant, high solubilizing po wer and low conductivity, as well as its amphiprotic character. It was shown that, unlike for most organic solvents, the electroosmotic flow is substantial. It was found to be possible to utilize NMF without ad ded electrolyte. Field strengths exceeding 1000 volts/cm could be empl oyed, while a low current was maintained and it was thus possible to o btain rapid analyses. Also, the properties of NMF allowed the analysis of substances with a low solubility in aqueous media. These features are exemplified by separation of carboxylic acids and pharmaceuticals. Excellent reproducibility of migration and no sign of electrical brea kdown were observed, even under high field strength conditions.