The size distribution of a core shell (SunShell) particle is much narrower than that of a conventional fully porous
particle, so that the space among particles in the column reduces and efficiency increases by reducing Eddy
Diffusion (multi-path diffusion) as the A term in Van Deemter Equation
.
Comparison of Particle Size Distribution
Wide particle distribution (Conventional silica gel D
90
/D
10
=1.50
)
Narrow particle distribution (core shell silicaD
90
/D
10
=1.15
)
As shown in the left figure, a core
shell particle has a core so that the
diffusion path of samples shortens
and mass transfer becomes fast.
This means that the C term in Van
Deemter Equation reduces. In other
words, HETP (theoretical plate) is
kept even if flow rate increases.
Packing state of core shell and fully porous silica
Flow of mobile phase
Why does a 2.6
µ
m core shell particle show the same performance
as a sub 2
µ
m particle?
0.5
2
4
D
10
: 1.75
µ
m
D
50
: 2.01
µ
m
D
90
: 2.31
µ
m
D
90
/D
10
=1.32
D
10
: 1.67
µ
m
D
50
: 2.09
µ
m
D
90
: 2.65
µ
m
D
90
/D
10
=1.59
(
µ
m)
0.5
1
2
D
10
: 2.46
µ
m
D
50
: 2.63
µ
m
D
90
: 2.82
µ
m
D
90
/D
10
=1.15
Company F, 2
µ
m
Sunniest, 2
µ
m
SunShell, 2.6
µ
m
2.0
µ
m
sample
Diffusion
Ca. 2.0
µ
m
sample
Diffusion
Sample
emanates in a
particle after it
enters.
Comparison of diffusion path
kept even if flow rate increases.
A 2.6
µ
m core shell particle shows
as same column efficiency as a fully
porous sub-2
µ
m particle.
The right figure shows that a
diffusion width of a sample in a 2.6
µ
m core shell particle and a 2
µ
m
fully porous particle. Both diffusion
widths are almost same. The 2.6
µ
m
core shell particle is superficially
porous, so that the diffusion width
becomes narrower than particle
size. Same diffusion means same
efficiency.
2.0
µ
m
Totally
porous
2.6
µ
m
1.6
µ
m
Core Shell
Diffusion of sample in core shell and fully porous silica
Plate Back press. (MPa)
Plate/back press
.
Sunniest C18 –HT 2.0
µ
m
9,900
16.7
593
Brand A C18 1.9
µ
m
7,660
16.3
470
Brand B C18 1.8
µ
m
10,100
19.6
515
Brand C C18 1.7
µ
m
11,140
32.0
348
SunShell C18 2.6
µ
m
9,600
9.7
990
Sunniest C18 –HT 2.0
µ
m
Brand A C18 1.9
µ
m
Brand B C18 1.8
µ
m
Brand C C18 1.7
µ
m
SunShell C18 2.6
µ
m
Column: 50 x 2.1 mm C18, Mobile phase: Acetonitrile/water=(70/30), Temperature: 25
o
C
Comparison of Performance by Plate/Pressure
Under a constant back pressure
condition, SunShell C18 showed
more than 2 times higher
performance to compare with fully
sub-2
µ
m porous C18s.
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