Enhancement of electroosmotic flow using zwitterionic additives.
Zwitterionic additives provide a means of altering the EOF without increasing conductivity. The magnitude of the EOF in a bare silica capillary increased by as much as 69% upon addition of 500 mM of zwitterion to the running buffer. The EOF enhancement increases linearly with the zwitterion concentration. With zwitterionic additives of the form +NH3-(CH2)n-COO-, the magnitude of the EOF increase is directly related to the number of methylene groups, (n), which ranges from n = 1 to 7. The endgroups on the zwitterions also affect the EOF enhancement. The effect of Z1-methyl (+N(CH3)3CH2CH2CH2SO3-) on EOF was not a function of either the buffer cation or pH. The EOF enhancement is a function of the dielectric increment of the additive and the nature of the amine functionality.
MacDonald
Amy M
AM
Department of Chemistry, University of Alberta, Gunning/Lemieux Chemistry Centre, Edmonton, Alberta, Canada.
Sheppard
Mary A W
MA
Lucy
Charles A
CA
D000596:Amino Acids / Q000737:chemistry*; D002021:Buffers; D004553:Electric Conductivity; D004573:Electrolytes / Q000737:chemistry*; D019075:Electrophoresis, Capillary; D009995:Osmosis; D000644:Quaternary Ammonium Compounds / Q000737:chemistry*; D014783:Viscosity
D000596:Amino Acids; D002021:Buffers; D004573:Electrolytes; D000644:Quaternary Ammonium Compounds