Nonaqueous capillary electrophoresis with alcoholic background electrolytes: separation efficiency under high electrical field strengths.
The effect of high voltage on capillary electrophoresis (CE) separations of anionic analytes in nonaqueous separation media was investigated. Methanol, ethanol, 1-propanol, and 1-butanol were tested as background electrolyte (BGE) solvents. Experiments were carried out with a laboratory-built CE instrument suitable for high-voltage separations. Potentials up to 60 kV were applied with reversed polarity to generate unusually high field strengths (e.g. 2000 Vcm-1) and so achieve fast and efficient separations. Highest separation efficiencies were obtained with propanol as BGE solvent, and the dependency of the efficiency on the separation voltage was more or less linear. With the other alcohols, separation efficiency decreased or remained roughly constant with increasing absolute voltage. The separation efficiencies are discussed in terms of longitudinal diffusion, Joule heating, and analyte interaction with the capillary wall. Capillary preconditioning had a varied effect on the separations in the different BGEs as the BGE and the conditioning process affected the electroosmotic flow (EOF) velocity and direction.
Palonen
Sami
S
Laboratory of Analytical Chemistry, Department of Chemistry, University of Helsinki, Finland.
Jussila
Matti
M
Porras
Simo P
SP
Hyötyläinen
Tuulia
T
Riekkola
Marja-Liisa
ML
D020001:1-Butanol; D000433:1-Propanol; D004553:Electric Conductivity; D004573:Electrolytes; D019075:Electrophoresis, Capillary / Q000379:methods*; D000431:Ethanol; D000432:Methanol; D013696:Temperature; D013997:Time Factors
D004573:Electrolytes; D000431:Ethanol; D020001:1-Butanol; D000433:1-Propanol; D000432:Methanol