How do I set limits and baselines in OmniSEC?

Setting limits and baselines is required in OmniSEC to tell the software which area of the chromatogram represents sample and which represents the baseline. Setting baselines and limits must be done for both calibration and analysis of the system and the data. Since setting baselines and limits is inherently subjective, it is recommended to be consistent whenever analyzing the data. This will ensure that different results are comparable and that different users will obtain similar results.

The instructions below, describe how to set limits and baselines. There are a number of other ways of doing this within the software; however, the instructions below describe the simplest way to perform these steps.

Setting limits around a peak

Holding down the "shift" key and clicking a left click on the mouse, will place the first of two limits. A second left click will place the second of the two limits that define an individual peak. In order to select a peak the user should:

1. Move the mouse cursor to the point where the peak first starts to increase.
2. Hold "shift" and click the left mouse button once.
3. Release the "shift" key.
4. Move the mouse cursor to the point where the peak finishes.
5. Click the left mouse button once.

Defining the baseline

Holding down the "shift" key and clicking a right click on the mouse, will immediately place the first of two baseline points. A second right click will place the second of the two points to define a baseline. In order to define a baseline, the user should:

1. Move the cursor to a point early in the chromatogram where the baseline is stable.
2. Hold "shift" and click the right mouse button once.
3. Move the mouse cursor to a point late in the chromatogram where the baseline is stable again.
4. Hold "shift" and click the right mouse button once.

Removing limits and baselines

If limits or baselines have been put in the wrong place, right click anywhere in the chromatogram and select "Delete All Limits" or the "Delete All Baselines". These will be removed and the process of setting limits and baselines can be re-started.