Solid supports for on-line selection and concentration in capillary electrophoresis

VIZIOLI NM

Florianópolis

Simposio; 16th Symposium on Biomedical, Biopharmaceutical and Industrial Applications of Capillary Electrophoresis and Microchip Technology; 2010

Preconcentration techniques using solid supports in capillary electrophoresis are based on the coupling of a microcolumn in the inlet of the capillary for selection and concentration of compounds prior to their electrophoretic separation. Such devices, commonly known as ?analyte concentrators?, can not only be used for concentration enrichment, isolation, or extraction of analytes but also to achieve microreactions, allowing the on-line analysis of reaction products. The selective adsorbents can be immobilized directly on a portion of the inner surface of the capillary wall, a membrane, beads, monolithic structures, or even a multibore capillary. In comparison with off-line solid phase extraction (SPE) columns, concentrators require lower sample volumes, only few microliters of organic solvent or buffers are consumed, the entire process is carried out in the CE instrument, and small quantity of sorbent material is needed, which make on-line SPE cheaper than the off-line one. In addition, sensitivity in CE is increased at least 102-104-fold, permitting the detection of analytes from 1 ng/mL with UV absorbance detector to 1 pg/mL with a LIF detector, and even femtograms per milliliter. Different examples of on-line concentrators used for analyzing a wide range of compounds will be discussed during this presentation. Special attention will be paid to main factors influencing concentrator performance e.g., the solid support geometry, chemical properties of the sorbent, sample concentration, and volume of elution buffer. Finally, the potential of on-line SPE in CE will be demonstrated through various applications carried out by our research group.