Empower Tip: Empower User Question AnsweredTip #406: Building and Searching Libraries of Derivatives of UV spectra

QUESTION:

How do I build libraries of derivatives of UV spectra and search against such a library?

Great question. Let’s see how it’s done!

Start with a mixture of known compounds and apply an appropriate Method Set.

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In Spectrum Review, click on the Spectra tab and, in the Deriv. Level field you can select a Derivative for a Spectrum. In this case, select Second. Repeat for all spectra of interest.

Deselect any derivatives for the UV spectra that are not of interest, then go to Library, New Library.

Enter a name for the Library and click Create.

Now you can add derivatives to the Library. From the Library menu, select Add to Library (name of Library). Enter a name for the derivative and any descriptive information. Click OK and repeat for every derivative you want to include in the Library.

Add the Name and Library Name fields to the Spectra table. These fields display the names of the derivatives you have added to the Library and the name of the Library.

Now select a sample, apply the Method Set, and select the derivative of the UV spectrum of interest. Be sure to deselect any derivatives and/or spectra which are not of interest.

From the Library menu, select Match Parameters and be sure to select Second Derivative, and check the Symmetrical Filtering box, and click OK.

From the Library menu, select Match Against (name of Library).

Click the Library Match tab and view the results listed in the order of best to worst match.

Automate the Library search via the Processing Method. Click on the PDA Library Search tab, select Second Derivative, and check the name of the Library you want to search against.

Save the changes to the Processing Method and reapply the Method Set. We see the results of the Library matches in the Peaks tab under the chromatogram.

NOTE: Empower does use the Derivatives of the Spectra to perform the library search, however, Spectrum Review, Match Plot, and Triple Plot will display the UV spectra.

It’s that easy!