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4.3.1 Automatic Operation
(Default)
4.3.2 Manual Operation
4.4 Mobile Phase
Considerations
7. Press
|
MENU
POWER
If temperature setpoints are reentered or operating conditions
change, the pump stops automatically in either mode. The screen
will display the message
display information about why the pump stopped.
In automatic mode, the pump will not run until all temperature
setpoints are met and gas pressure is correct. When all operating
conditions are met or restored, the pump automatically activates.
In manual mode, when all operating conditions are met or
restored, the screen will display the message
prompt you to press
AUTOZERO
Selecting a Solvent
High purity mobile phase solvents with low boiling points are
recommended for use with the ELSD. Solvents should be spectral
or HPLC grade. Dirty or contaminated solvents will cause
baseline noise and drift, blocked fluid paths, and a build up in
the detector. All solvents used should have less than 1ppm of
residue after evaporation and filtered to less than 0.45µm. Sol-
vents can be evaluated by pumping them directly into the
detector, and comparing the noise to other known solvents. We
have found that not all HPLC grade solvents are acceptable for
use with an ELSD. Preservatives commonly used in Tetrahydro-
furan (THF), will increase the noise level. If unstabilized THF is
used, ensure that it is fresh. THF can contain peroxides that can
increase noise and are potentially explosive if taken to dryness.
Mobile Phase Flowrate and Composition
The recommended flowrate for the ELSD is 0.25mL/min to
3mL/min. The mobile phase flowrate will affect baseline noise. In
general, more baseline noise will be generated by higher flowrate
of a mobile phase.
The ELSD will operate with common HPLC solvents that are vol-
atile enough to form a vapor under the operating conditions. This
includes common HPLC solvents such as water, methanol, aceto-
nitrile, acetone, isopropyl alcohol, and THF. Normal phase sol-
vents such as dichloromethane and hexane may also be used.
Note that solvents with higher boiling points will generally
result in more baseline noise. These should be used in limited
percentages or at a lower flowrates.
Buffer Compatibility
The ELSD is not compatible with mobile phase modifiers that
are not volatile, such as salts. Some modifiers are volatile and
can be used. These include but are not limited to acetic acid, tri-
fluoroacetic aid (TFA), formic acid, triethylamine, and ammonia.
The concentration of buffer in the mobile phase should be as low
as possible.
Section 4 Operation
to return to the home screen.
. Press
NOT READY
MENU
ALMOST READY
to restart the pump.
340CF ELSD
|
to
POWER
and
4-13
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