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This paper presents an analytical and parameterized model
for analyzing the effects of Joule heating on analyte dispersion
in electrophoretic separation microchannels. We first obtain
non-uniform temperature distributions in the channel resulting
from Joule heating, and then determine variations in
electrophoretic velocity, based on the fact that the analyte’s
electrophoretic mobility depends on the buffer viscosity and
hence temperature. The convection-diffusion equation is then
formulated and solved in terms of spatial moments of the
analyte concentration. The resulting model is validated by both
numerical simulations and experimental data, and holds for all
mass transfer regimes, including unsteady dispersion processes
that commonly occur in microchip electrophoresis. This model,
which is given in terms of analytical expressions and fully
parameterized with channel dimensions and material properties,
applies to dispersion of analyte bands of general initial shape in
straight and constant-radius-turn channels. As such, the model
can be used to represent analyte dispersion in microchannels of
more general shape, such as serpentine- or spiral-shaped
channels.
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