Varian CP

Varian CP
 Varian CP-3800 GC
GC SAMPLE PREPARATION:
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Sample Components to Avoid Completely:
The following should never be injected: metals, strong acids or bases, salts, oligomeric
and polymeric material. These classes of compounds are unsuitable for gas
chromatography, and can damage the GC column.
Solvents:
Hexane, acetone, and methanol are the recommended solvents for sample preparation.
Other acceptable options are benzene, ethers, and methylene chloride. Do not dissolve
samples in water, DMSO, or DMF.
TURNING ON THE INSTRUMENT:
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Turn the Nitrogen (80 psi on regulator), compressed air (60 psi) and hydrogen (40 psi)
gas tanks on. Note: If the gas in any of the tanks fall below 300 psi, the cylinder should
be replaced.
Turn on the Gas chromatograph. The power button is on the top left side of the
instrument.
Make sure the computer controlling the instrument is turned on and open the Galaxie
software.
Use the following user name: User1.
METHOD DEVELOPING AND EDITING:
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Under the File tab click on Open a Method. If a method is not already developed begin by
opening FID.METH and proceed to save method as desired method name.
Select the method on interest and click on the Open button.
Once the Method of interest appears under the Data Files dialog box proceed to alter the method
by following the Data, System and Calibration tabs at the bottom left of the control page.
Click on control icon in the Data tab. This will open a dialog box in the split screen (Fig. 1) in
which many parameters can be altered.
Click on the Autosampler (8400) icon and make sure the ENABLED box is checked. The
Syringe volume should be set to 10 µL, the Injection mode to Std (Split/Splitless), the sample
and solvent penetration set to 90%. Default and Clean Mode can be altered to desired number of
washes pre and post injection. Make sure the solvent source is filled with the desired solvent!
Figure 1. Autosampler- Control Method.
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Click on the Injectors icon. Only the front is installed and active. Make sure the Heater is set to
ON and input the Setpoint to desired temperature. The set point should be set to 25°C warmer
than the final column temperature or about 50°C warmer than the boiling point of the analyte.
The split event table can be used to add or subtract events at injections. In order to increase
injection volume without overloading the injector the following is a common event table for
Split/Splitless injection:
Time (min)
Split Rate
Split Ratio
1
Initial
ON
20-100
2
0.01
OFF
20-100
3
0.75
ON
20-100
If the concentration of the analyte is not too dilute, simply setting one event to slit rate On and
split ration between 20-100 will be sufficient.
Click on Column Oven icon. This will allow controlling of the temperature ramp and the length
of the experiment. Adjusting the Rate (°C/min temperature will increase), the Temperature to be
reached and the length of Time for each step will allow to optimize experimental conditions.
Figure 2. Column Oven- Control Method.
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Click on Column Pneumatics icon. For most experiments, constant flow should be enabled and
the column flow set to 1.0 mL/min. However it is possible to also to run pressure pulse
experiments by disabling Constant Flow and setting up Rate, Pressure and Time events.
Click on the Detectors icon. Both the Heater and the Electronics should be set to ON. The set
point of the FID heater should be similar to the final column temperature (usually 250-300 °C).
The Time constant and Range can be altered to modify the data collected. A fast time constant
and a range of 12 (10-12 Amp/mV) is amenable to most experiments. Autozero should be set to
YES. The Type 11 EFC window will show the set points for the individual gas flows.
Figure 3. Detector Gas Setpoints.
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Once all the parameters are set, proceed to save the method and make sure the changes are loaded
to the Gas Chromatograph by clicking on the Overview button under control in the Data tab, and
press on the first icon with a red arrow. This will transfer all settings to the instrument to the
default Method 8.
Figure 4. Communication to and from the GC.
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If the FID is not on or you experience a flame out, assure the parameters have been sent to the
instrument and check the detector is on by putting the provided stopper and metal column on the
detector, and check for vapor against a shiny object.
Click on Acquisition in the data tab at the bottom left of the screen and proceed to enter the
experiments parameters. File prefix will be applied to all runs carried out under the same
conditions, Sample properties and Column parameters are optional, but Acquisition
parameters should reflect the correct Vial # and Acquisition length. Check Autoscale or set up
parameters for the data collected in the Working Scale portion.
SEQUENCE DEVELOPING AND EDITING:
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Under File select Open Sequence and proceed to modify and save settings from Start-up
sequence.
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In the sequence control window it is possible to add and remove events, set up runs of
multiple samples with the same method or changing methods in the analysis of the same
samples:
In the event table, the Enabled column will assure the sample will be run, the Method
must be entered as well as the Vial # and the Inj. Volume. Other parameters are optional.
Figure 5. Sequence Editing.
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Once the sequence has been edited, proceed to Save the settings and press the green arrow
button to begin the desired runs. It is possible at any point to stop the run by pressing the red
stop button.
It is possible to monitor the status of the GC and the progress of the run by clicking on the
Systems tab and expanding both the Chromatogram and Status tab under the 3800 System
semaphore. Toggling between the Overview and the GC icon on the bottom panel will allow for
monitoring of different settings on the GC.
Figure 6. System Monitoring.
ANALYSIS:
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Once the chromatogram has been collected it is possible to reprocess the data at any time.
To do so click on the Integration event under the data tab to Set Peak Width and
Threshold and to determine when to Turn integration on, in order to ignore solvent
peaks during integration. This can be altered post run and reprocess the chromatogram as
needed.
Other setting can be accessed by using the right mouse button to add as many integration
events as needed.
4 Figure 7. Integration Events.
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In order to view result, under File click on Open Chromatogram and select the data sets of
interest. In the top left window, the data sets will appear with three possible views: Data to solely
view the chromatogram, Method to view the integration events as well and the Results in order
to view the result table as well as the chromatogram.
In order to zoom in, hold the left mouse button and drag over the area of interest from top left to
right bottom. To zoom out, invert the action from right bottom to top left.
Click on Print under the File tab to print a standard report.
A series of icons in the top toolbar allow to reprocess the chromatogram by altering the Peak
Markers, Labels, Add Peaks, and Split Peaks among others options. Once these settings are
altered, it is necessary to Reprocess the data. Under the Processing tab it is possible to
Reintegrate and Reprocess the data. After doing so proceed to save changes and print new
results.
Figure 8. Data and Results.
SHUTTING DOWN THE INSTRUMENT:
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Proceed to load the Cool Off Method. This will turn down gas flows and turn off the detector.
Once the instrument has been cooled for about 30 minutes, proceed to turn off the GC with the
main switch on top of the instrument, and close all three gas tanks: H2, Air and N2.
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