Spermine-graft-dextran non-covalent copolymer as coating material in separation of basic proteins and neurotransmitters by capillary electrophoresis

Spermine-graft-dextran (Spe-g-Dex) copolymer was synthesized and used as a non-covalent coating for the separation of proteins and neurotransmitters by capillary electrophoresis. The coating was obtained via flushing the capillary with 1.0% Spe-g-Dex copolymer solution for 2 min. Electroosmotic flow (EOF) was strongly suppressed, ranging from -1.60 x 10(-9) to 3.65 x 10(-9) m(2) V(-1) s(-1). Effect of experimental conditions, such as the copolymer concentration, the concentration and pH of the background electrolyte (BGE), on the Spe-g-Dex coating was investigated. Separation of lysozyme, cytochrome c, ribonuclease A and et-chymotrypsinogen yielded high separation efficiencies ranging from 141 000 to 303 000 plates/m and recoveries from 85.4% to 98.3% at pH 4.0 (284.0 mM sodium acetate-acetic acid buffer, l =50 mM). Run-to-run repeatabilities and day-to-day, and capillary-to-capillary reproducibilities were all below 1.7%. In addition, Spe-g-Dex coating allowed the successful separation of five neurotransmitters, 5-hydroxytryptamine, dopamine, epinephrine, isoprenaline, dobuamine at pH 4.0 with high separation efficiencies of 290 000-449 000 plates/m. (C) 2010 Elsevier B.V. All rights reserved.