Extract intensity of mass ranges

[Giulia Ricciardi]

Hello everyone,

I've recently started working on MSI data and my project requires the extraction of the intensity of several ions to compare their abundances in different samples. 

Although I have learned with the help of this group how to extract the intensity of one ion, I still haven't figured out how to extract a range of ions.

Example: I have a tissue section and I want to extract the intensity of m/z 1523.758+- 0.003, so I would need to have the intensity values of this m/z range: 1523.755 - 1523.761, and not only the one from the main ion 1523.758.

Is there a way to do it?

Here is the line of code I'm stuck with:

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intensity <- spectra(file)[features(file, mz=1523.758),]

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Then I can go ahead and convert this into a data frame, but I would only get the intensity values of the selected m/z and not of the 'surrounding' ions.

Thanks in advance for the help!

Giulia