CE in a nonuniform capillary modulated by a cylindrical insert, and zone-narrowing effects during sample injection.
The electrophoretic behavior of an analyte in a capillary consisting of two parts of different cross section has been investigated. Modulation of the cross-sectional area of the separation channel has been achieved by inserting a cylindrical fiber different distances into the capillary. It was shown that the zone injected into the capillary part with smaller cross section could be moved using electromigration into the wider part of the capillary with zone compression. As we observed, the zone narrowed longitudinally in the wide part of the capillary in accordance with the ratio of the electric field strength in the two parts of the capillary. The concentration of plug introduced into the capillary by electroinjection can be increased by use of low-conductivity sample buffer. Efficient introduction of extracted analytes desorbed from an SPME fiber to the separation channel was achieved using this approach. Thermoinduced effects caused by temperature increase in the narrow part of the capillary and their influence on sample stacking are analyzed. Possible applications of the effect observed to the sample introduction optimization are also discussed in this study.
Stoyanov
Alexander V
AV
Liu
Zhen
Z
Pawliszyn
Janusz
J