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Enhancement of electroosmotic flow using zwitterionic additives
Author(s) -
MacDonald Amy M.,
Sheppard Mary A. W.,
Lucy Charles A.
Publication year - 2005
Publication title -
electrophoresis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.666
H-Index - 158
eISSN - 1522-2683
pISSN - 0173-0835
DOI - 10.1002/elps.200500431
Subject(s) - zwitterion , conductivity , chemistry , amine gas treating , analytical chemistry (journal) , flow (mathematics) , chemical engineering , chromatography , organic chemistry , molecule , mechanics , physics , engineering
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 + NH 3 ‐(CH 2 ) 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(CH 3 ) 3 CH 2 CH 2 CH 2 SO 3 − ) 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.