Büchi Labortechnik AG
Product description | 3
Operation Manual Sepiatec SFC-250
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5 °C
70 °C
50 °C
1
Pumps
2
Column oven
3
Detector, flow cell
4
Back pressure regulator
5
Post-heater
6
Gas-liquid-separator
7
Fractions (8 pcs.)
8
Liquid CO
2
60 - 75 bar
9
Pre-cooling
10 CO
2
pump
11 Modifier pump
12 Sample
13 Modifier stream injection
14 Supercritical CO
2
80 - 250 bar
15 BPR pressure value 80-250 bar
16 Add-on pump
17 Low pressure
18 CO
2
exhaust
19 Depressurized fraction collection
The mobile phase in supercritical fluid chromatography consists of a supercritical
fluid and a liquid solvent. This fluid is a condensed gas above the critical temperature
and pressure. Its properties are those of a gas and liquid. Carbon dioxide (CO
2
) is
mostly used.
The CO
2
is transported by the pump in a cooled state. The fluid gets heated above
the supercritical temperature in the column oven and mixed with the modifier. The
back pressure regulator maintains an elevated pressure to keep the mobile phase
above the critical point of CO
2
. The sample is then transported over the separation
column by the supercritical fluid. A modifier can be added to improve the elution of
organic substances.
After detection, the CO
2
is separated from the eluted substances. The Detection and
Fraction valve position decides in which GLS the stream is going. The GLS separates
most of the CO
2
and removes it from the system by an exhaust pipe and fed into the
ventilation system.
