Magic Triangle Tool for SEC/GPC Column Selection
The Magic here is not a "random lucky
strike". It is PSS ability to design stationary phases that cover
the full range of
polarity, inherently, thus preventing interactions between polymer and
stationary phases during a SEC analysis.
The PSS Magic Triangle is a visual aid for
the quick selection of analysis matrix, where the three sides
represent sample, mobile phase, and stationary phase. By applying
the principle of "like dissolves alike" you will ensure
interaction free GPC/SEC chromatography. Generally, the
sample polarity mandates the
polarity
of the solvent and consequently that of the stationary phase and
calibration standard.
 
Construct a triangle by drawing a base line from the
polarity of a sample to the mobile phase, draw a perpendicular from the
middle of the segment and the Magic Triangle will form pointing to the
appropriate
stationary phase.
This concept is also applicable for aqueous GPC/SEC. The magic triangle
for aqueous systems takes the pH value instead of the stationary phase
into account.
The tool also works to decide what kind of calibration standard will
work better under given conditions, or what pH will work best with a
given column.
Additional Column
Selection Considerations:
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1- Field of Application
|
Column Choice |
|
Product screening at
constant peak resolution
Analysis time: ~ 12 min per sample
|
Analytical mixed bed
(linear) columns |
|
Highest resolution
and maximum information
Analysis time: > 12 min per sample
Use the column
combinations recommended by PSS to avoid column mismatch.
|
Multiple analytical
single porosity columns (combination)
comparison linear vs. column combination
|
|
Very fast results
needed in process control and high throughput screening
Analysis time: 2 - 4 min per sample
|
HighSpeed columns |
|
Solvent saving, small
sample amounts
|
Microbore columns |
|
Preparative sample
fractionation, sample collection
|
Preparative columns |
|
GPC/SEC-light
scattering or Triple detection
|
Lux columns |
Aqueous |
Suprema
SupremaLux
Proteema
Novema
MCX
|
Organic |
SDV
SDVLux
GRAM
POLEFIN
POLEFINLux
|
2- Column Particle Size |
from 3
μm up to 20 μm |
Higher
solvent viscosity
|
Higher
particle size |
| High
Sample Molar Masses |
Higher
particle sizes. |
3- Column
Porosity |
30
Å to 10 000 Å |
| To
separate low molecular weight products |
use
small porosities. |
| higher
molecular weight |
higher
porosity |
Single porosity columns
show a high resolution in a narrow molecular
weight range. A wide molecular weight range at constant high resolution
is covered when columns with single porosities are coupled in series
(column combination).
Examples for single porosity columns:
* SDV 1 000 Å, separation range: 100 - 60 000
Da
* GRAM 3 000 Å, separation range: 5 000 - 5
000 000 Da
* SUPREMA 1 000 Å, separation range: 100 - 1
000 000 Da
Examples for recommended column combinations (series of single
porosity
columns):
* SDV 100 Å + 1 000 Å + 10 000Å +
precolumn (low molar masses)
* GRAM 30 Å + 1 000 Å + 1 000Å +
precolumn (medium molar masses)
* SUPREMA 100 Å + 3 000 Å + 3 000Å
+ precolumn (high molar masses)
Linear or mixed bed columns provide a very wide porosity range
therefore offering a broad separation range with a smaller resolution.
Examples for linear columns:
* SDV linear M separation range: 100 - 1 000 000 Da
* GRAM linear, separation range: 500 - 1 000 000 Da
* SUPREMA linear XL, separation range: 1 000 - 4 000
000 Da
In all cases use precolumns
for the protection of the main columns.
PSS offers a wide variety of column dimensions and will manufacture
custom sizes upon request.
Type
I.D
x Length (mm)
Guard columns 8 x 50; 4,6 x
30; 20 x 50
Analytical
8 x 300 and 8 x 600
Microbore
4,6 x 250
Preparative
20 x 600
HighSpeed
20 x 50
Analytical, HighSpeed and
guard
Columns may be purchased online. Email us for a custom quote for
analytical columns (8x600), Microbore and Preparative columns.
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