PerkinElmer CLARUS 590 GC, Руководство пользователя

Страница: 96 / 284

96 . Clarus 590 GC User’s Guide
11. Touch the Initial time dialog box and use the up and down arrow or keypad buttons
to enter an initial time.
12. Touch the Initial rate dialog box and use the up and down arrow or keypad buttons
to enter an initial rate value that decreases the pressure down to the operating pressure in psi/min.
13. Touch the step 2 dialog box for pressure and use the up and down arrow or keypad
buttons to enter the column operating pressure.
NOTE: If you selected flow or velocity, you should still follow the above procedure. Just enter the appropriate flow
or velocity values for your analysis.
NOTE: If you are in the capillary mode, and you set up the pressure mode first, you can enter 70 psi and/or 10
psi, then read the appropriate flow or velocity values respectively. This helps determine the values to use.
This technique is also recommended for the Clarus GC/MS detector. With mass spectrometers, you must be
careful not to overload the vacuum chamber. In order to avoid this, the setup procedure is slightly different
than the above procedure. You would not want the initial pressure when using the TurboMass Gold to be
too high, because at the end of the GC run all parameters are set back to their initial values, and the higher
pressure could cause damage to the vacuum system.
For the Clarus GC/MS detector the initial value is set to the normal operating pressure (flow or velocity) and
a negative timed event with a high pressure (flow or velocity) will be added to the method. This causes the
pressure (flow or velocity) to increase prior to Ready (for example, prior to the injection). At injection, the
GC method holds this pressure (flow or velocity) for the time necessary to transfer the sample onto the
column. The experimentally determined pressure (flow or velocity) is then programmed at a controlled rate
down to the initial (or normal) column operating pressure (flow or velocity).
If you are using the autosampler, at the end of the last sample in the sequence, the GC/MS will go “Not
Ready,” thereby sending a signal to the Clarus GC keeping it from coming Ready. (The External Ready
must be connected.
See the
Clarus GC Installation Guide, 09936590
.) This keeps the GC from executing the negative timed
event and holds the pressure at the lower setting.
Setting the Split Flow for Splitless Injection
To make a splitless injection, initially turn Off the appropriate split flow that is associated with your injector
with a timed event. Then with another timed event, turn it On from 0.25 to 2 minutes into the GC run and
leave it on. When the GC run is complete, the Clarus GC returns the split flow to its initial setting.
To set up for splitless operation:

From the Injector status screen touch the dialog box for Split flow and use the up and down arrow or
keypad buttons to enter a split flow in mL/min.