Analyzing DSC Calibration Data

 

Before analyzing the DSC cell constant, temperature, or baseline calibration data you will need to conduct the necessary calibration experiments. See DSC Cell Calibration for information. Once the calibration experiments are complete, as indicated by a check mark next to the run numbers (s) on the sequence list, access the Calibration Analysis window by selecting Calibrate/Analysis or click the   button.

Calibration results may be analyzed and saved after each DSC calibration experiment or all together (e.g., after all the experiments have completed).

NOTE:  Tzero calibration data is analyzed using the Calibration Wizard.

NOTE:  The "heat flow" signal should be selected and used to measure the heat of fusion or enthalpy of sharp melting transitions such as obtained with Indium.

Using the Analysis Window

  1. The calibration program will automatically try to determine the calibration type (baseline, cell constant, or temperature) and the standard used (if required) from the information in the data file. The letter B, C, or T will appear next to each run indicating the calibration type—baseline, cell constant, or temperature respectively.  The program will then display the data and analyze the curve according to the default calibration settings. Baseline calibrations will automatically determine the analysis limits markers based on the method used. No input is required.

  2. If the correct calibration type is not selected, click the Select Type button (or choose Select Type from the pop-up menu). The DSC Calibration Analysis Specification window is displayed.  Choose the type of calibration desired and, if applicable, the standard to be used. (A standard is needed for DSC cell constant or temperature calibration.) Then click OK. The file is plotted on the plot area of the calibration window.

  3. To choose the standard setting, click on the Setup button.  See also:  Setting Up Calibration Standards

  4. If the results are acceptable, all you need to do is save the results for each calibration by clicking on the Accept button (or by choosing Analyze/Accept results from the pop-up menu). These results will be automatically sent to the instrument.  Once the data has been saved a check mark will appear next to the file within this window.  

  5. To reanalyze the curve, click on the Analyze button (or choose Analyze from the pop-up menu) to display the limit point markers. Position the markers for the desired analysis limits. Press Enter or select the Limits OK button (or select Limits OK from the pop-up menu) to calculate and display the calibration results.

  6. Rescale the plot, if desired.  This can be done using the mouse to expand part of the curve. You can select Prev(ious) Scale or Full Scale to display previous scaling.

  7. Print the results, if desired, by clicking on the Print button (or by choosing Print from the pop-up menu).

  8. If more than one listing appears in the file list, click on each file (run) to view, modify (if necessary) and save the data.  In addition, to open a new calibration file, repeat the steps above.

  9. Click the Close button to close the analysis window.

Use the Analyze calibration submenu to select different analysis options. You can analyze the current data file; accept, delete, and show results; choose limits for your data file; etc.

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Performing the Analysis

To analyze the data in your calibration file, perform the following steps:

  1. Select the  Analyze button (or select Analyze from the Calibration menu). The current limit points will be indicated with markers on the graph.

 NOTE:  The active marker is indicated by a full-length vertical red line. Other markers are indicated by smaller red cross-hairs.

  1. Move the active marker to the desired position on the curve using either the mouse or keyboard (see the directions below).

  2. Select (activate) the next marker by:  (a) Pressing the TAB key or (b) Positioning the pointer over a marker and clicking the left mouse button. (Pressing back TAB (Shift-TAB) will activate the previous marker)

  3. Repeat steps 2 and 3 until you have selected all the necessary points for analysis.

  4. Select the Limits OK button (or select Limits OK from the pop-up menu) to accept the  points. When calculated, the calibration results will be displayed.

  5. Accept the calibration results by selecting the Accept button (or by selecting Analyze/Accept results from the pop-up menu). You can delete results by selecting the Delete button (or by selecting Analyze/Delete results from the pop-up menu).

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Moving the Markers Using the Mouse:

  1. Position the pointer at the desired location.

  2. Double-click mouse button 1 to move the active marker to this point. This action causes the next marker to become active.

or

  1. Position the pointer over the active marker.

  2. Press and hold down the left mouse button while you drag the marker to the desired location.

  3. Release the mouse button. At this point you may use the arrow keys to position the marker more closely (see the directions below).

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Moving the Markers Using the Keyboard:

Press the arrow keys to move the active marker to the desired position.

The marker will move in the following increments:

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