title: Chirally functionalized anion-exchange type silica monolith for enantiomer separation of 2-aryloxypropionic acid herbicides by non-aqueous capillary electrochromatography.
abstract: A silica based monolithic capillary column derivatized with O-9-(tert-butylcarbamoyl)quinidine was prepared for CEC enantiomer separation of chiral 2-aryloxypropionic acid herbicides including inter alia dichlorprop, mecoprop and fenoprop. The silica monolith had a relatively low surface coverage with chiral cationic selector moieties. Due to the low selector density retention factors were low as well, yet still enabling enantiomer separations of the target solutes. Both electrophoretically and chromatographically dominated migration and separation modes, respectively, could be established depending on the employed conditions. In the former mode, enantiomers migrated in front of the EOF marker, and faster separations and higher plate numbers could be achieved. In the latter mode, stronger adsorption translated into a typical chromatographic separation in which the enantiomers eluted after the EOF marker whereby separation factors were slightly enhanced compared to the aforementioned separation mode. Reasonable baseline separations of enantiomers were accomplished for all analytes after optimization of relevant mobile phase parameters in the anion-exchange CEC system including sample loadability, and the separations were comparable to such obtained on an optimized high density quinidine-carbamate modified organic polymer monolith column. Overall, it is concluded that monoliths with a high surface density of chiral ion-exchange moieties are favorable because of their enhanced sample loadabilities and improved chromatographic performance with regard to separation factors, plate numbers and peak symmetries. The resultant accompanying longer analysis times may rather be reduced by adjusting effective column length than by reducing selector coverage of the monolith.
authors.affiliation: Christian Doppler Laboratory for Molecular Recognition Materials, Department of Analytical Chemistry and Food Chemistry, University of Vienna, Vienna, Austria.
authors.forename: Stefanie
authors.initials: S
authors.lastname: Buchinger
authors.forename: Beatrix
authors.initials: B
authors.lastname: Follrich
authors.forename: Michael
authors.initials: M
authors.lastname: Lämmerhofer
authors.forename: Dieter
authors.initials: D
authors.lastname: Lubda
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Lindner
mesh_terms: D015085:2,4,5-Trichlorophenoxyacetic Acid / Q000031:analogs & derivatives / Q000302:isolation & purification; D015084:2,4-Dichlorophenoxyacetic Acid / Q000031:analogs & derivatives / Q000302:isolation & purification; D053801:Capillary Electrochromatography / Q000379:methods*; D006540:Herbicides / Q000302:isolation & purification*; D009994:Osmolar Concentration; D011422:Propionates / Q000302:isolation & purification*; D012822:Silicon Dioxide / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: D006540:Herbicides; D011422:Propionates; D015084:2,4-Dichlorophenoxyacetic Acid; D012822:Silicon Dioxide; D015085:2,4,5-Trichlorophenoxyacetic Acid; C009264:fenoprop; C010571:dichlorprop