BUCHI Extraction System B-811 LSV - Manual (Page 25)

4 Description of function
25 B-811 Operation Manual, Version G
completely evaporated, a few milliliters of solvent are automatically released into the beaker. Again, this
solvent evaporates, a temperature increase on the heating element’s sensor is detected and again a
few milliliters of solvent are released. This occurs three times. After the third solvent drain is happened,
several milliliter of solvent remain in the beaker. Then the heating element is automatically turned off
and the position stands in the wait mode. Within 30 minutes all positions should have reached this
status, before the program switches to step 3. Otherwise an error 5 is displayed individually on the
relevant position.
4 .4 .3 Drying - Step 3 (to 9)
When the program switches to step 3, the heating elements are powered on
again according to the level set in the program. Usually the heating level is
reduced in order to prevent the extract from an overheating. The solvent is
evaporated while the valve is closed and collected in the extraction chamber.
The following steps (3 to 9) allow the heating power to be reduced levelwise,
which provides a mild drying.
A drying under inert gas is available using the inert gas option. It is activated
by pressing the INERT GAS key in the relevant step and remains active until
the end of the step or the entire program is finished. In case of oxygen-sensi-
tive analytes inert gas is supplied during processing. Heat-sensitive analytes
should not be extracted to complete dryness; add a keeping solvent (high-
boiling point solvent) prior to extraction to prevent overheating of the analyte.
Fig. 4.11: Procedure of Drying - Step 3-9
4 .5 Programming
4 .5 .1 Extractions without rinsing and without drying
Step 1: Enter parameters of step 1 and switch to step 2.
Step 2 - 9: Set parameters to 0. Store program.
Table with parameters to be entered:
Soxhlet Standard Soxhlet Warm Hot Extraction Continuous
Step 1 lower heating
level
Extraction
time and / or
number of
cycles
upper and lower
heating level
Extraction time
and / or number of
cycles
upper and lower
heating level
Extraction time
lower heating
level
Extraction time
Step 2 lower heating level = 0
rinsing time = 0
Step 3 - 9 lower heating level = 0
drying time = 0
At the end of the program the solvent containing the extract remains in the beaker.