SOP (Standard Operating Procedure)
for the Perkin-Elmer Pyris 1 DSC
Table of Contents
1. Preparing the DSC for operation
1.1 Turning on the system
1.2 Checking the DSC configuration
1.2.1 Checking the DSC firmware version
1.2.2 Checking the Pyris software version
1.3 Connecting the peripheral gases
1.3.1 Nitrogen gas
1.3.2 Helium gas
1.4 Filling the cryofill
2. Operating the DSC
2.1 Equilibrating the DSC
2.2 Baseline adjustment
2.3 DSC calibration
2.3.1 Temperature calibration
2.3.2 Heat flow calibration
2.3.3 Furnace calibration
2.3.4 Calibration reference materials
2.4 Running the DSC
2.4.1 Preparing the sample
2.4.2 Inserting the sample into the DSC
2.4.3 Programming your DSC run
2.4.4 Starting and monitoring the DSC run
3. Post processing
3.1 Baseline correction
3.2 Onset calculation
3.3 Peak area calculation
3.4 Specific heat calculation
1. Preparing the DSC for operation
1.1 Turning on the system
Power up the system using the following steps :
(Step 1) Turn ON the computer
(Step 2) Turn ON the DSC by pressing the switch on the rear panel of the DSC as shown on the right. If the DSC indicator panel is lit up the DSC is ON.
(Step 3) Turn ON the cryofill by pressing the switch on the cryofill control box.
(Note) Powered ON standby :
The entire system is usually kept ON even during standby. However, you should be aware that the sample chamber may reach temperatures ~ 40 degC during non-operation.
1.2 Checking the DSC configuration
You need to check the DSC configuration to ensure proper operation. Two items need to be confirmed, the DSC firmware version and the Pyris software version.
1.2.1 Checking the DSC firmware version
If you are certain that the firmware version is 6.4(or higher) skip this section.
The DSC firmware version can be checked by performing the following procedures :
(Step 1) From the Windows desktop select :
Start -> Programs -> Pyris Software for Windows -> Pyris Configuration
(Step 2) : The Pyris configuration window will appear as shown on the right. Comunication should be with COM2 and the ‘Analyzers’ column should display the Pyris 1 DSC as connected and recognized. From this screen, press the Edit button.
(Step 3) : The Pyris 1 DSC configuration window will appear as shown below. At the time of installation no gas accessories were included and the only checked box should be for the Cryofill. Press the Firmware Version button. WARNING : Do NOT press the update Flash EPROM button unless you are attempting (after having consulted Perkin-Elmer) to rewrite the system’s Firmware.
(Step 4) : The PyrisCfg window should indicate that the firmware version is version 6.4(or higher). Version number is displayed as the last two digits of an unbelievably long garble of characters. If the version is incorrect, you must update the firmware after conferring with Perkin-Elmer and receiving adequate information on performing the procedure correctly and safely.
(Notes) Installation history :
The Pyris 1 DSC was installed in our lab with the factory default firmware version 6.0 and then upgraded to version 6.4 using a single floppy installation disk.
(Notes) Problems with earlier Firmware versions :
The only problem noticed with older versions is a strange phantom glass transition which occurs at around -127 degC during measurements. This phantom change occurred even when the sample pan was empty. This can cause a sudden discontinuity in specific heat measurements before and after the nonexistent transition.
1.2.2 Checking the Pyris software version
If you are certain that the software version is 3.72(or higher) skip this section.
The Pyris software communicates and controls the DSC from our computer. It is also used for post-processing previously-performed DSC runs. The software version can be checked by performing the following procedures :
(Step 1) From the Windows desktop select :
Start -> Programs -> Pyris software for windows -> Pyris Manager
(Step 2) An embedded Pyris manager toolbar will appear on the screen. Press the Pyris 1 DSC button.
(Step 3) The Pyris software main window will appear. You should be able to see the ‘Instrument Viewer’ and ‘Method Editor’ windows inside the main window. The ‘Control Panel’ should also be embedded on the main window.
(Step 4) From the main window toolbar, select : Help -> About…
(Step 5) The About Pyris window should appear and indicate the software version as 3.72(or higher). If the version is incorrect, you must update the software after conferring with Perkin-Elmer and receiving adequate information on performing the procedure correctly and safely.
(Notes) Installation history :
The Pyris 1 DSC was installed in our lab with the factory default software version 3.7 and then upgraded to version 3.72 using a single floppy installation disk.
1.3 Connecting the peripheral gases
Our DSC uses two types of gases during operation. Nitrogen gas is used as shield gas and is also supplied to the cryofill. Helium gas is used as purge gas and is supplied to the sample chamber. Both gases pass through drierite columns to remove residual moisture.
1.3.1 Nitrogen gas
Nitrogen gas is provided to both the DSC shield gas inlet and the cryofill gas inlet.
The supplied gas pressure should be 40 psi.
There is a secondary pressure regulator between the drierite and the shield gas inlet which controls the amount of gas flow when the DSC slide cover is opened. If you feel the shield gas flow is inadequate to prevent external moisture and particles from entering the sample holders, increase the flow by turning the knob of the secondary regulator located on the rear corner of the DSC.
1.3.2 Helium gas
Helium gas is provided to the DSC purge inlet. The supplied gas pressure should be 25 psi.
(Note) Do NOT use nitrogen gas for subambient DSC runs. Nitrogen gas will liquefy at temperatures near -196 degC or earlier.
1.4 Filling the cryofill
The cryofill needs to be filled with liquid nitrogen using the following steps :
(Step 1) If you haven’t done so already, open the Pyris software.
(Step 2) Enable BOTH the shield gas and cover heater by pressing the buttons on the Pyris control panel. Depressed buttons are at the ON state.
(Step 3) Connect a liquid nitrogen supply tank to the cryofill inlet valve using a cryo line(hose) but do not open any valves yet.
(Step 4) Open the cryofill vent valve completely, but allow the valve to be loose and not completely be jammed in the counterclockwise direction. You may have difficulty closing the valve if you do so due to ice formation around the valve handle.
(Step 5) Open the cryofill inlet valve valve completely, but allow the valve to be loose as described above.
(Step 6) Open the liquid nitrogen(LN2) tank supply valve slowly and observe the pressure buildup in the cryofill. Pressure around 9 psi is normal, but should not exceed 12 psi. If the pressure is too high, reduce the inflow of LN2 accordingly. You will observe nitrogen gas escaping through the cryofill vent during the filling procedure. If the cryofill was empty to begin with, the hissing sound can become quite loud. It will recede when the cryofill has been filled to a certain degree. When the cryofill is almost completely filled, LN2 will sporadically burst out from the vent. This is a good time to end the filling as described in the next step. Remember to protect yourself from LN2 freeze burns with cryo gloves and protective garments.
(Step 7) Close the valves in the following order :
LN2 supply tank valve -> Cryofill inlet valve -> Cryofill vent valve
(Step 8) Immediately loosen the cryo line(hose) to prevent pressure build-up inside the line(hose). One usually maintains the connection on the cryofill inlet valve and loosens only the connection on the LN2 supply tank valve.
All preliminary setup is now complete and the DSC is ready for operation.
2. Operating the DSC
2.1 Equilibrating the DSC
The DSC needs to be filled with LN2 from the cryofill prior to performing runs and measurements.
(Step 1) If you have not done so already, turn ON all system components and open the Pyris software. See Chapter 1 for more information.
(Step 2) Make sure the peripheral gases are being supplied to the system and check the cryofill level gauge to see if there is enough LN2 for your runs and measurements.
(Step 3) If you have not done so already, enable BOTH the shield gas and cover heater by pressing the buttons on the Pyris control panel. Depressed buttons are at the ON state.
(Step 4) Enable the cryofill button on the Pyris control panel. The ON state will indicate the cryofill button in a BLUE color. The cryofill will now start pumping LN2 into the DSC. It takes at least 2 hours for the DSC to stabilize.
(Note) It is always a good idea to prevent the sample holder temperature from becoming subambient during the equilibration process. You should monitor the temperature being displayed on the DSC indicator panel. If the temperature is becoming too low, set the furnace to heat the sample holders manually by entering a number (25 degC is a good choice) in the input box of the control panel and then pressing the manual go to temp button.
2.2 Baseline adjustment
Baseline adjustment is performed to manually level the DSC curve and slope. It should be performed only when a substantial change in the DSC hardware component or system setup has occurred. The adjustment procedure is composed of three steps :
> Manual baseline optimization
> Baseline curvature correction
> Baseline slope adjustment
Further information concerning the procedure is available in the Pyris help module loaded on the computer.
(Note) Baseline correction :
Baseline correction is performed for most DSC runs using the Pyris software during postprocessing. This is due to the fact that the DSC thermogram cannot be completely level during the runs and will be explained in the postprocessing section. However, the software baseline correction should not be confused with the hardware baseline adjustment described above.
2.3 DSC calibration
Calibrating the DSC consists of three components :
> Temperature calibration
> Heat flow calibration
> Furnace calibration
You should normally perform the calibrations in the order described above. It is especially important to note that a furnace calibration should be done AFTER a temperature calibration.
The calibration section describes procedures with which you may yet not be familiar with. Refer to other portions of this document for the described procedures as required.
All sample measurements for calibration purposes should be repeated at least 3 times and averaged, using the run procedure you would normally use (cooling rate, temperature range, etc.)
2.3.1 Temperature calibration
1. While in the Instrument Viewer or the Method Editor, select Calibrate from the View menu.
2. Restore the default Temperature calibration by selecting Temperature from the Restore menu. If you are performing all of the calibration procedures, restore all default calibration values by selecting the All command.
3. Select the Save and Apply button in the Calibration window to send the default calibration values to the analyzer and save the current calibration file.
4. Select Close to close the Calibration window.
5. Complete a scan for each reference material under the same conditions that you run your samples.
6. Perform a Peak Area calculation and include the Onset temperature. Record the ΔH (J/g) and Onset results; you will need the Onset result for Temperature calibration and the ΔH result for Heat Flow calibration.
7. Repeat steps 5 and 6 for each additional reference material to be used.
8. Select the Calibrate command in the View menu. The Calibration window appears.
9. Select the Temperature tab. Enter the name of the reference material used, the expected Onset value, and the Onset result just measured for each reference material.
10. Select the check box in the Use column for each reference material to be used in the calibration.
11. Select the Save and Apply button in the Calibration window to send the new calibration values to the analyzer and save the current calibration file.
Go on to the next calibration procedure by clicking on its tab or select Close to close the Calibration window and begin using the new calibration values.
2.3.2 Heat flow calibration
1. While using the Instrument Viewer or the Method Editor, select Calibrate from the View menu.
2. Restore the default Heat Flow calibration by selecting Heat Flow from the Restore menu. If you performed a Temperature calibration just prior to starting a Heat Flow calibration and selected All from the Restore menu, then you do not need to restore the default Heat Flow calibration here.
3. Select Save and Apply.
4. Select Close.
5. Complete a scan using a reference material or use one that was run for the Temperature calibration.
6. Perform a Peak Area calculation and note the ΔH (J/g) result. You can also use the ΔH result recorded for one of the reference materials used in the Temperature calibration.