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4.4.1 Create and Subtract Baseline with Peak Analyzer


Summary

In OriginPro, the Peak Analyzer is capable of creating and subtracting baseline. There are various ways for baseline creation. You can generate baseline anchor points automatically or manually and then connect them with interpolation or fit them with a function.

Minimum Origin Version Required: 2016 SR0

What you will learn

  • How to create baseline with 2nd Derivative method
  • How to create baseline with Asymmetric Least Squares (ALS) Method (Pro)
  • How to subtract a baseline from the spectrum

Steps

Create baseline with 2nd Derivative method

  1. Start a New Workbook and import the <Origin EXE Folder>\Samples\Spectroscopy\Baseline.dat. Highlight the second column. In the main menu, select Analysis: Peaks and Baseline: Peak Analyzer to open the dialog of the Peak Analyzer.
  2. In the first page (the Goal page) of the Peak Analyzer, select Create Baseline as Goal. Click Next to go to the Baseline Mode page.
    Goal.png
  3. Next we are going to create an user defined baseline for this spectrum by defining anchor points. On the Baseline Mode page, select User defined from the Baseline Mode dropdown list. Check on Snap to Spectrum to make sure when you add or move a baseline anchor point, it will be pulled back onto the spectrum.
  4. The first two methods in Anchor Points Finding are the most commonly used, and they can find anchor points automatically based on the derivative of the spectrum. If the baseline is approximately constant, 1st Derivative and 2nd Derivative is more powerful, otherwise, we should use 2nd Derivative. In this example, the baseline is more curly, so we use 2nd Derivative method for locating anchor points.
    For other methods in Anchor Points Finding and related smoothing parameters, you can refer to the link: Baseline Mode Page.
    Baseline mode-v1.png
  5. Now click the Find button in the Baseline Anchor Points group. You can preview the anchor points in preview window.
    Anchor preview v1.png
  6. Click Next to go to the Create Baseline page, select Interpolation in the Connect by drop-down list. In Interpolation method group, select Spline from the drop-down list. You can preview the spectrum in preview window, and then click Finish to get the baseline data.
    Baseline previews v1.png
    Baseline previews v2.png

Create baseline with ALS Method (Pro)

  1. Start from the Baseline Mode page, and select the Asymmetric Least Squares Smoothing Baseline (ALS) as the baseline method. The ALS baseline can be tuned easily with a few parameters without pre-selecting any anchor points.
    ALSmethod.png
  2. Click Next go to Asymmetric Least Squares Smoothing Baseline page, adjust the parameters to make the baseline optimal, then click Finish button to output the results table and graph.

ALSmethod2.png

Subtract Baseline from a Spectrum

  1. If you want to subtract baseline, select Subtract Baseline as the Goal at start page.
  2. After you created a baseline, click Next button to go to Subtract Baseline page.
  3. Click Subtract button for previewing the subtracted data. The baseline data and subtracted spectrum will be outputted after clicking Finish button. The figures below displayed the Subtract Baseline page and the preview of the subtracted spectrum.
    Subtract baseline.png
    Subtracted data.png
 

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