How to create curves

Introduction

You can draw a curve of your own in the Evaluation module. This section describes how this is done.

Note: The right to create and rename curves is defined in the user access rights and may be restricted.

How to create curves - step 1

The table below describes how to set up a chromatogram window to create a curve in the Evaluation module.

Step

Action

1

Open a result file.

2

Select Operations:Create Curve.

Result: The Create Curve dialog box opens.

3

Select one or more Help curves.

4

Select

  • minimum and maximum values for the Y-axis.

  • appropriate units from the Unit list.

Note: The help curve determines the minimum and maximum values for the X-axis.

5

Click OK.

Result: The Create Curve chromatogram window opens.

How to create new units

In the Create Curve dialog box you can also create new units for the curve. The table below describes how this is done.

Step

Action

1

Click the New unit button.

Result: The Create New Unit dialog box opens.

2

Type a new unit name and a number of decimal places.

3

Click OK.

Result: The Create New Unit dialog box is closed. The new unit is now available in the Create Curve dialog box.

How to create curves - step 2

The new curve is created in the Create Curve window. The table below describes how to work in this window.

Step

Action

1

Click the Set Curve Points icon.

2

  • Click to insert curve points in the chromatogram.

  • Add more points to draw the curve.

Result: A green square marks the new curve point. The curve is drawn from the previous point. Hold the cursor over the inserted point to see the coordinates displayed.

Curve mode

  • The regular spline mode draws the curve as a smooth line near but not through every point.

  • Click the Spline through checkbox to draw the curve through all of the curve points.

3

Move a point

  • Select the point and drag it to the new position.

Result: The curve is redrawn.

4

Delete a curve point

  • Double-click the curve point.

or

  • Select the point and click the Delete button.

or

  • Select the point, right-click and choose Delete Point from the shortcut menu.

5

  • Click the Zoom icon to focus on details in the curve.

Note: Right-click and select Reset zoom to return to the full view.

  • Right-click in the chromatogram window and select Marker.

  • Position the Marker bar over peaks in the help curve to measure the coordinates.

Result: The coordinates are displayed in the Marker text box in the top left corner of the chromatogram.

Note: Click the Marker text box to display the coordinates for the created curve. Click again to return to the help curve coordinates.

6

Click OK.

Result: The Save Curve dialog box opens.

7

Type a new name if desired and click OK.

Curve example

The illustration below is an example of a curve created by using the Draw Spline command in the Create Curve chromatogram window.

How to force the curve through points

In cases where you have created a curve and not selected the Spline through option, you may want the curve to pass through some of the points that are outside the created curve. The table below describes how to force the curve through these points:

Step

Action

1

  • Select the curve point immediately before the curve point you want to connect to.

2

  • Click the Draw straight to next point button.

Result: The curve is adjusted so that it is drawn as a straight line between the two points.

2005-06-15