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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
F
l
o
w
o
f
m
o
b
i
l
e
p
h
a
s
e
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
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
T
o
t
a
l
l
y
p
o
r
o
u
s
2.6
µ
m
1.6
µ
m
C
o
r
e
S
h
e
l
l
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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