SOP for Differential Scanning Calorimetry (Perkin-Elmer DSC-7)

OBJECTIVE

Differential scanning calorimetry (DSC) monitors heat effects associated with phase transitions and chemical reactions as a function of temperature. In a DSC the difference in heat flow to the sample and a reference at the same temperature is recorded as a function of temperature. The sample is sealed in an aluminum pan. The reference is an inert material such as alumina, or just an empty aluminum pan. The temperature of both the sample and reference is increased at a constant rate.

SCOPE

The Perkin-Elmer DSC-7 differential scanning calorimeter is used to accurately measure melting points, glass transitions, and heat of fusion.

RESPONSIBILITIES

It is the responsibility of the QC Analyst to ensure adherence to this procedure.

It is the responsibility of the QC Manager to follow the instructions of this procedure.

PRECAUTIONS

• Never touch the outer and inner furnace lids. The temperature of the furnace can reach as high as 450°C. Use tweezers to remove the lids.
• Do not touch the inside of the furnace; it might be hot and internal pollution can cause a loss of performance.

PROCEDURE

• Turn on the power switch on the front of the DSC.

• Log into Windows.
• After Windows comes up, double-click the LOG ON icon. The LOG ON window will come up. Type in your username & password.

• After you login, the Pyris software will load. You will see a menu bar at the top of the screen, which will indicate that the DSC 7 is Offline. Click on the DSC 7 icon to bring it online:

• The DSC 7 window will come up.

• You should see temperature status information for the TGA 7 if everything is working properly:

• Fill the DSC with ice water, with the metal funnel in place.

• First, we need to run a blank spectrum to verify that the DSC was found in good condition. After you run your blank spectrum, print it out, and put your name on it and place it in the tray by the computer monitor. Before you run the blank, check to make sure that both the sample and reference furnaces are empty.

• After you have checked that both furnaces are empty, put their platinum lids on, close the swing-arm cover, and put the dome on top.

• Set the DSC to the starting temperature in your run.
• Set the DSC to the starting temperature in your run.
• Set the DSC to the starting temperature in your run.

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• Set the DSC to the starting temperature in your run.

• After the DSC status indicates that is “At Temp”, look at the Heat Flow reading, and wait until the Heat Flow is stable to 0.001 mW.

• Start the run by clicking on the Start Run button.

• After the run has started, click on the Instrument Viewer to monitor the progress of the run.
• Note that the default setting for the graph is to have “Time” displayed on the X-axis. If you want to change this to Temperature, click on the Display menu, and click on Rescale X, and you will see an option to change the X-axis to Temperature
• Please print out your blank spectrum, and put your name on it, and place it in the tray next to the computer monitor.

• To run an actual sample, you must first encapsulate your sample in a special aluminum sample pan. For instructions on how to do this, please see the Appendix on sample preparation. Place your sample pan into the middle of the sample furnace, and then put an empty aluminum pan into the reference furnace.

• Carefully put the platinum lids on top of each furnace, then secure the swing-arm cover over the furnaces, and then put the dome lid on top.

• Set up your data acquisition using the method editor

• Tell the DSC to go to your starting temperature

• When it is “At Temp”, monitor the Heat Flow. Wait until the Heat Flow is stable to 0.001mW. Then click on the Start Run button.

• Click on the Start Run button.

• To monitor the progress of the run, you can click on the Instrument Viewer window.

DSC Data Analysis

• To calculate the onset temperature, peak area, and enthalpy, click on the Calc menu, and click on Peak Area. Click on the option to include Onset. Position the X’s at the start of the peak, and at the end of the peak. Then click on Calculate

• You must then click on File, and Save Data, in order to save the calculated results with the raw data file.
• To convert a spectrum to ASCII format, click on the Edit menu, and click on Copy. Then go to a text program such as Word, and click on Edit and Paste. The sample data points and the acquisition parameters will be displayed in text format, and can then be saved.

How to shut down the DSC

• First, run another blank spectrum to show that you have left the DSC in good condition.
• Please print out the blank graph, put your name on it, and put it in the tray near the computer monitor.
• Click on the Start Pyris button, and then click on Close All. This will close the software.

• Log out of Windows.
• Turn off the DSC TAC (Thermal Analysis Controller).
• Turn off the power switch on the DSC.
• Turn off the nitrogen gas.

ABBREVIATION

QC: Quality Control

ANNEXURE

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REVISION HISTORY

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