Buchi SpeedExtractor E-914, Operation Manual

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6 Operation
36
SpeedExtractor E-916 / E-916XL / E-914 Operation Manual
6.2 Preparing the instrument
This section involves all steps required to make the instrument ready for operation.
3
! WARNING
Death or serious poisoning by contact or incorporation of harmful substances at use.
•
Before operation, check the instrument for correct assembling
• Before operation inspect sealings and tubes for good condition and tightness
• Exchange worn out or defective parts immediately
• Provide sufficient ventilation and make sure to directly withdraw fumes
6.2.1 Solvent reservoir
As already mentioned, when developing a new method, select a solvent or solvent mixture that is
already known from a classical method such as Soxhlet extraction or another high pressure method
such as ASE. Generally, the analytes should show high solubility in the extraction liquid, but not the
sample matrix.
Do not use solvents with an self ignition point of 40 to 220 °C.
Particularly, do not use the following solvents with the SpeedExtractor. If there is any question about
solvent suitability, contact BUCHI.
Solvents NOT being compatible with the process
Component Formula Reason
Carbon disulfide CS
2
Autoignition temperature 100 °C
Diethyl ether C
4
H
10
O Contains peroxide
1.4-Dioxane C
4
H
6
O Contains peroxide
Strong mineral or organic acids and bases Corrosive to metallic components
THF C
4
H
8
O Contains peroxide
Further aspects to consider:
• Use HPLC- or p.a. grade solvents.
• Generally, solvents do not need to be degassed; only if the analytes of interest oxidize easily.
• Weak acids and bases, such as acetic acid or potassium hydroxide, or other non-corrosive addi-
tives may be used in small portions, i.e. <5 % by volume, added to the solvent system. Hydrolyzed
food samples for fat determination can be used without any problems since the hydrolysed resi-
due is washed to a neutral pH prior to extraction.
NOTE
Prior to an extended shutdown after an extraction flush the system (both INTO VIAL and INTO
WASTE):
• with chlorinated organic solvents for 2 min with methanol
• with acidic or basic solvents with pure organic solvents such as ethanol or distilled water
See section 6.2.6 for a description of the flushing process.