INVESTIGADORES
KEUNCHKARIAN Sonia
congresos y reuniones científicas
Título:
Optimizing Conditions to Generate Frits in Capillary Microcolumns
Autor/es:
S. KEUNCHKARIAN, L. GAGLIARDI Y C. B. CASTELLS
Lugar:
Buenos Aires
Reunión:
Congreso; 18th Latin-American Symposium on Biotechnology, Biomedical, Biopharmaceutical and Industrial Applications of Capillary Electrophoresis and Microchip Technology; 2012
Resumen:
Since its first years Capillary
Electrodriven Chromatography (CEC) has demonstrated to be a promising separation
technique. The flat flow speed profiles and the virtually unlimited possibility
to extend the column lengths leads to efficiencies in the order of 100 000
theoretical plates or higher, this is, 10-fold or more of the typical
efficiencies obtained in HPLC. However, difficulties for the reproducible
production of capillary columns constituted an important drawback that make
HPLC techniques to lead the market of standard methods for the analytical
separation of liquids. One of the most important source of non-reproducibility
is the generation of the porous devices (frits) to retain the particle beds.
Due to the ?micro? scale, porous devices must be generated in-situ and
the control of the experimental conditions at these scales is naturally
difficult. Porous devices based on silica particles have some advantages since
it is the same material of the tube wall. They have excellent properties from
both, the mechanical and chemical point of view. Procedures described on
literature for sinterizing silica particles involve radial heating of the
capillary tube with electric resistances. This leads to radial inhomogeneities
across the frit, localized zones of strong electric fields heating and forming
bubbles, differences in permeability, peak dispersion and loss of efficiency.
Additionally, with these method it is difficult to control the frit length.
In this work we
introduce a method to obtain silica frits by frontal exposition of the extreme
of capillary tubes filled with silica particles to a controlled source of heat
(muffle oven). Experimental details and conditions, such as temperature,
exposition time, introduction of particles, etc., have been optimized. SEM
imaging, chromatographic and electrophoretic characterizations are also used to
study the frits generated in the different conditions.