DOSY for beginners
To process a DOSY successfully, you should be familiar with 1-D and 2-D processing.
- First set up iNMR to run scripts, if it is not already set up. If you have a Bruker spectrometer, add the file DOSYbruker.lua to your folder of scripts. If you have a Varian spectrometer, add the file DOSYvarian.lua instead.
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Set up the spectrum:
Open the spectrum in iNMR. Open the dialog Edit > Metadata. Under the column f1, change the name of the nucleus to “0-.” (zero dash dot). Do not edit the nucleus under the column f2. Close the dialog. - From the Scripts menu, select DOSYbruker or DOSYvarian, depending on your spectrometer. A message will appear in the console, like “19 values extracted and converted”. The number should match the number of rows in the spectrum.
- Extract the bottom row of the 2-D plot. Perform the Fourier Transform (without weighting) and phase correction. Close the 1-D plot with the command Close Extract. Apply the same FT on the whole matrix.
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Perform DOSY-specific processing:
Open the dialog Process > DOSY > Mono Exponential. For an initial analysis, choose “Logarithmic Scale”. Click on OK. -
Optimize processing:
Inspect the result. You may want to reduce the spectral width, thus increasing the resolution. This is more important on the vertical scale. Note the narrowest limits of the scale that encompass all the peaks. - Restart the process using the commands: File > Reload; Process > Fourier Transform; Process > DOSY > Mono-Exponential. Now you can try changing a few parameters. Their meaning is explained here.
- If you are not satisfied with the new result, go back to step 7 and change the parameters again.