Page 29 - BR20828_E Accucore 0713S

Technical Note 20755
Comparison of Solid Core HPLC Column
Performance: Effect of Particle Diameter
Luisa Pereira, Thermo Fisher Scientific, Runcorn, Cheshire, UK
Introduction
The use of partially porous particles is gaining momentum
as they provide higher efficiency than fully porous
particles of equivalent particle size. Initially introduced
with a particle size in the range 2–3 µm, they are now
commercially available in a range of particle sizes, from
sub-2 to 5 µm. This gives the chromatographer the
flexibility of being able to select the most appropriate
particle size for each specific assay; however, it may not be
clear what the most suitable particle size is. This technical
note partially addresses this gap in information by
providing advice on what particle size to select under
which experimental conditions. We compare the
performance of the Thermo Scientific™ Accucore™ XL
4 µm and Accucore 2.6 µm particle packed columns.
Accucore HPLC columns are based on Core Enhanced
Technology™, which features solid core materials with a
very tight particle size distribution and advanced bonding
technology to functionalize the surface. The particles in
the Accucore stationary phases can be described as a solid
silica core surrounded by a porous outer layer. The very
tight particle size distribution of these materials results in
columns with high permeability. Therefore, for the same
nominal pressure, Accucore provides better separations
than fully porous materials.
Equation 1, known as the Blake-Kozeny equation, shows
the dependency of the pressure drop across the column on
a variety of experimental parameters under laminar flow
conditions. It can be seen that the pressure is directly
proportional to the column length, flow rate, and mobile
phase viscosity and inversely proportional to the square of
the particle size diameter and the square of the column
internal diameter. The interstitial porosity (the spaces
between the particles that are accessible by the mobile
phase) has a more complicated relationship to the
Key Words
Solid core, fused core, superficially porous, pressure, efficiency, impedance
Abstract
In this technical note, the chromatographic performance of solid core 4 µm
and 2.6 µm particle-packed columns is compared. Parameters compared
are column pressure, efficiency, and impedance.
pressure. There are other operating parameters that will
have an impact on the overall system pressure. Some of
these are the inner diameter and length of the connecting
tubing in the LC system, the detector set-up parameters,
such as flow cell volume in UV, or the inner diameter and
length of the capillary components in ESI or APCI sources
in LC/MS.