Buchi SpeedExtractor E-914, Operation Manual

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6 Operation
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SpeedExtractor E-916 / E-916XL / E-914 Operation Manual
to 1/3 and 2/3 of the final pressure. The HEAT UP time is defined as the time during which the
pressure remains at 1/3 of the total pressure. A further prerequisite is that the temperature of the
heating block reached its equilibrium. It is a method-dependent intrinsic parameter which depends
mostly on the size of the extraction cell and is therefore not adjustable by the operator.
• Hold time
The hold time corresponds to the static extraction time during which the temperature and pressure
remains constant. This time period is only determined by the nature of the sample and hence set
by the operator.
• Discharge time
Time used to discharge the extraction cells by means of pressure compensation. Make sure the
time is long enough to empty the cell completely.
Close consideration of the process shown above reveals that there are two variable time periods
between the tightness test and the heat up and the heat up and the hold step, respectively. These pe-
riods depend on the process parameters, the sample's property and packing in the cell, and the size
of the extraction cell. The accurate values are therefore only available in hindsight. The remaining time
used to finish process which is shown in the main and the progress display, is based on rough estima-
tions for these periods. Slight changes, observable by leaps in time, are therefore possible.
• Next cycle or Flushing the system
After the last extraction cycle is finished and the extract is discharged, the lines are flushed with
solvent first, followed by nitrogen to thoroughly empty the lines. Make sure that the flush with sol-
vent and gas are long enough to avoid carryover due to analyte residues of the last cycle (flush with
solvent) and to avoid a blow back of the sample due to solvent residues (flush with gas).
6.4.3 Creating new methods
A summarized overview of all extraction parameters as well as recommended default values are given
in section 6.4.4.
Open the submenu EDIT METHOD:
• To create a new method open EDIT METHOD in
the EXTRACTION menu. Use the selection knob
to set the values for the temperature and pressure
according to your procedure.
As a rule of thumb it is recommended to set the
temperature approximately 20 – 30 °C over the
boiling point and the pressure to 100 bar.