Page 25 - BR20828_E Accucore 0713S

Technical Note 20640
Comparison of Solid Core HPLC Column
Performance
Luisa Pereira, Thermo Fisher Scientific, Runcorn, Cheshire, UK
Introduction
The use of partially porous particles, with a diameter
between 2 and 3 µm, is gaining momentum, as these
provide similar efficiency to sub-2 µm particles but with
significantly lower column backpressures.
The Accucore HPLC column range uses Core Enhanced
Technology™ to produce a 2.6 μm solid-core material
with a very tight particle size distribution. The particles in
the Accucore columns are not fully porous but instead
have a solid silica core surrounded by a porous outer
layer. The very tight particle size distribution results in
columns with high permeability. Therefore, “bar for bar”,
Accucore columns produce improved separation efficiency
when compared to fully porous materials.
Equation 1, known as the Burke-Plummer equation,
shows the dependency of the pressure drop across the
column on a variety of experimental parameters. The
pressure is directly proportional to the column length,
flow rate, and mobile phase viscosity and is inversely
proportional to the square of the particle size diameter
and the square of the column internal diameter ID. The
interstitial porosity (the spaces between the particles
that are accessible by the mobile phase) has a more
complicated relationship to the pressure. There are other
operating parameters that have an impact on the overall
system pressure, such as the ID and length of the
connecting tubing in the LC system, detector setup
parameters, such as flow cell volume in UV or the ID and
length of the capillary components in ESI and APCI
sources in LC/MS.
Key Words
Solid core, fused core, superficially porous, pressure, efficiency, impedance
Abstract
In this technical note the performance of Thermo Scientific™ Accucore™
HPLC columns is compared to a number of competitive columns. The
experimentally derived parameters that are used for the comparison are
column pressure as a function of flow rate, efficiency, and impedance.
Equation 1
where ΔP = pressure drop across the column
a = constant (dependent on packing,
normal values in the range 150 -225)
εi = interstitial porosity of the packed bed
F = flow rate through the column
L = length of the column
η = viscosity of the mobile phase
dp = particle diameter
dc = column internal diameter
E =
∆P t
N η 2
∆P = a η F L (1 - ) 2
d 2
c d 2
p 33
i
3i