Extending The Degassing Flow Rate Range; Shutdown; Short-Term Shutdown (Overnight And Weekends) - Knauer Smartline 5000 Serie Handbuch

Vacuum Degasser Unit

Extending the degassing flow rate range

Shutdown

Short-term Shutdown (Overnight and Weekends)

Since there is virtually no solvent retained within the Vacuum
Degasser (~480 microliters per channel), priming the system is
relatively simple. Using a flow rate of 2 mL/min with the Smartline
Pump 1000 for 1-2 minutes ensures that the line from the analytical
degasser channel being primed through the proportioning valve on
the pump has freshly degassed solvent. If you are using the
semipreparative Version the values will be accordingly higher. This
dynamic priming method will allow an immediate startup of the
analysis upon column equilibration. Contrary to previous PTFE-
based degassers, the new Vacuum Degasser, which uses Teflon
®
AF membranes, fully degasses solvents within the time it takes for
the volume to pass through the chamber, and yet degasses the
solvents as thoroughly as, or better than, PTFE channels containing
40 times more solvent.
Certain organic solvents used in reversed phase chromatography outgas
upon mixing with water, if not properly degassed. These solvents are
generally alcohols (e.g. methanol), acetonitrile and tetrahydrofuran.
Passing water and methanol through a single channel is generally
sufficient to degas these solvents so outgassing does not occur upon
mixing when a 75% methanol: 25% water mixture is generated by your
Vacuum Degasser or pump at a flow rate of 5 mL/min. If outgassing does
occur, or if a high flow rate is required, it is a general rule that only the
organic portion of the mobile phase needs to be passed through a
second degassing channel to ensure outgassing does not occur. This is
due to the ability of all organic solvents (e.g. methanol) to hold at least 10
times more dissolved atmosphere than water can.
To more thoroughly degas a mobile phase, connect the outlet of the
organic channel to the inlet a second channel and the outlet of the
second channel to the pump. This places the two channels in series and
doubles the degassing capacity for the organic portion of the mobile
phase.
There are two types of shutdown procedures: long-term and short-term.
Observe all precautions pertaining to hazardous solvents and/or those
solvents that form harmful deposits or by-products.
1. Flush the column according to the instructions supplied with the
column. Flush buffer salts from the system with water. Evaporation
leaves salt crystals that may form harmful deposits. Remove
chloroform or solvents that can decompose to form hydrochloric acid
from the system.
Damage caused by precipitating buffer salts in capillary tubing, or
damage resulting from this condition, is specifically excluded from
warranty.
2. Remove harmful mobile phases from the Vacuum Degasser and
other instruments in the system by carefully purging with pump.
3. After removing harmful mobile phases, prepare the degasser for
most mobile phases by flushing it with isopropanol. To avoid
contaminating the system, refilter or discard solvents
(including water) that were exposed to the environment for
more than 24 hours before use.
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