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New isoelectric buffers for capillary electrophoresis: N-carboxymethylated polyethyleneimine as a macromolecular isoelectric buffer

Citation

Macka, M and Johns, CA and Grosse, AC and Haddad, PR, New isoelectric buffers for capillary electrophoresis: N-carboxymethylated polyethyleneimine as a macromolecular isoelectric buffer, Analyst, 126, (4) pp. 421-425. ISSN 0003-2654 (2001) [Refereed Article]

DOI: doi:10.1039/b100608h

Abstract

Isoelectric buffers are attractive for electrophoresis because of their low conductivity, and their compatibility with indirect photometric detection in capillary electrophoresis (CE) where they do not interfere with the detection by exhibiting competitive displacement of the UV-absorbing probe ion. N-carboxymethylated polyethyleneimine (CMPEI) was prepared by introducing a half molar equivalent of carboxylate groups onto a polyethyleneimine backbone. Its isoelectric point determined by conductometric titration and from the pH of its dilute aqueous solution is approx. 6.8, which allows isoelectric buffering at a lower pH compared to histidine (pI 7.7). Although the isoelectric point is somewhat diffuse, as expected for a polymeric compound, it exhibits a buffering capacity at a pI point of about twice that of histidine. Studies of electroosmotic flow (EOF) profile at various pH values in fused silica capillaries showed that CMPEI adsorbs onto the fused silica wall and reverses the EOF at pH < 6.5. CMPEI was applied as a buffer in an electrolyte containing 0.5 mM of the anionic dye tartrazine used as the probe for indirect detection of anions. The separation system exhibited a stable baseline, no system peaks, separation efficiencies of up to 195 000 theoretical plates, and detection limits down to 0.2 μM or 2 amol of injected analyte.

Item Details

Item Type:Refereed Article
Research Division:Chemical Sciences
Research Group:Analytical Chemistry
Research Field:Separation Science
Objective Division:Expanding Knowledge
Objective Group:Expanding Knowledge
Objective Field:Expanding Knowledge in the Chemical Sciences
Author:Macka, M (Professor Mirek Macka)
Author:Johns, CA (Dr Cameron Johns)
Author:Grosse, AC (Mr Andrew Grosse)
Author:Haddad, PR (Professor Paul Haddad)
ID Code:22142
Year Published:2001
Web of Science® Times Cited:9
Deposited By:Chemistry
Deposited On:2001-08-01
Last Modified:2011-08-03
Downloads:0

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