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Decreased protein peak asymmetry and width due to static capillary coating with hydrophilic derivatives of polydimethylacrylamide
Author(s) -
Cretich Marina,
Stastna Miroslava,
Chrambach Andreas,
Chiari Marcella
Publication year - 2002
Publication title -
electrophoresis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.666
H-Index - 158
eISSN - 1522-2683
pISSN - 0173-0835
DOI - 10.1002/1522-2683(200207)23:14<2274::aid-elps2274>3.0.co;2-y
Subject(s) - coating , chemistry , capillary electrophoresis , silanol , capillary action , chromatography , epoxy , adsorption , covalent bond , chemical engineering , materials science , organic chemistry , composite material , engineering , catalysis
We have recently described [1] a fast and simple method for the “adsorbed static” coating of capillaries in capillary zone electrophoresis (CZE) with epoxy‐poly(dimethylacrylamide) (EPDMA). Protein CZE peaks in the EPDMA‐coated capillaries exhibited a peak asymmetry similar to that obtained in capillaries with “covalent static” coating of polyacrylamide, suggesting a similar degree of adsorption of the protein onto the coating [2]. Instability of such coating at very low ionic strength and its stripping from the capillary in the presence of sodium dodecyl sulfate (SDS) also indicated a hydrophilic bonding of EPDMA to the silanol surface of the capillary, while its stripping in the CZE of “carboxylate‐modified” polystyrene suggested a competition between carboxylate and EPDMA for the hydrophilic bonds to silanol. To test those propositions, a number of EPDMA‐derived coating agents with increased hydrophilicity were synthesized. Of a number of the hydrophilic coating agents tested (Table 1) only two, 2% hydrolyzed EPDMA (HPDMA) hydrolyzed in sulfuric acid to effect the conversion of the epoxy groups to diols (Table 1, No. 38), and 20% EPDMA (Table 1, No. 44) exhibited for representative proteins a decreased peak asymmetry and width while the stability of the suppression of electroosmotic flow (EOF), and the stability of mobility in consecutive CZE runs was reduced relative to EPDMA. Coating agents which were more highly hydrophilic than those two (Table 1, No. 49) or less hydrophilic than 2% EPDMA (Table 1, Nos. 57, 53, 46) provided no stable static coating.