SAMPLE INJECTION IN CAPILLARY ELECTROCHROMATOGRAPHY: ASSESSMENT OF SPLITTER UTILIZATION
| Title in English | SAMPLE INJECTION IN CAPILLARY ELECTROCHROMATOGRAPHY: ASSESSMENT OF SPLITTER UTILIZATION |
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| Authors | |
| Year of publication | 2005 |
| Type | Article in Proceedings |
| Conference | Procceding of 11th International Symposium on Separation Sciences |
| MU Faculty or unit | |
| Citation | |
| Field | Biochemistry |
| Keywords | CEC; separation |
| Description | Sample injection is an important part of any electroseparation analysis. There are at least two arguments why to optimize the sample injection scheme: The first is good repeatability of injected sample volume as the basic demand to ensure reproducible CEC analysis. The second one is the effort to minimize extra-column band broadening caused by sample injection to preserve high efficiency of CEC separation. Present injection schemes are based on electrokinetic or hydrodynamic principle. The injection can be implemented by dipping of capillary end into the sample reservoir, the use of injection valves (rotary-type injector with 2-6 ports) or utilization of a splitter. All these means have its disadvantages and limitations. The dipping method shows low repeatability and injection valves have fixed injected volume. The use of the splitter seems to be the best choice. The continuous flow of mobile phase guarantees a constant supply of fresh mobile phase. It prevents the separation system from buffer depletion and pH changes and simultaneously it allows the gradient elution. The problem is the sample dilution in transport capillary that interconnects the sample injection device with the splitter. The suitable solution can be the utilization of splitter working in the heart-cut regime. We studied mechanisms of spontaneous (diffusional) and electrokinetic sample injection. We also performed automated CEC separations of standard mixture and evaluated repeatability of isocratic, gradient and preconcentration analysis. We achieved high repeatability not only peak heights and areas (RSD ~ 2%) but also retention times (RSD ~ 0.5%) due to automated CEC instrument constructed in our laboratory and with laboratory made monolithic columns. |
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