Purity Calculator script
Purity Calculator script |
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This new script can be run without a license of the qNMR plugin. You will only need a license of the NMR module. This script is located under the 'Tools/NMR Tools' menu:
The script method is still heavily used in some Development labs as a final check of compound purity. The spectra used must be of high quality with good shimming, acquired with sufficient time between pulses for full relaxation (typically 20-40 s in DMSO-d6). For processing the spectrum should be well very well phased (manually), and baseline corrected. The example shown here is typical and doesn’t present problems. Practical problems that may arise could be a large broad OH signal (which can sometimes be sharpened by adding a little TFA), or careful baseline correction. Other examples also require that you determine the salt ratio – but we don’t deal with that here. Just load the sample spectrum (which you can download from here) and follow the menu 'Tools/NMR Tools/Purity Calculator' in order to fill in the sample details and choose the reference compound with the applicable molecular mass of the internal reference and its purity (you can load, modify and add to the reference compound details by loading the csv file that you downloaded in the previous step):
Clicking on OK, you will be prompted to integrate the signal that will be used as reference compound.
In that case, we will manually integrate the signal at 5.74ppm and click on the 'Continue' button:
Now, we will integrate 3 multiplets for the analyte (choosing the aromatics close by). Once these have been integrated, click “Continue” again.
Clicking on the 'Continue button will display the dialog box below: From that dialog box, if it is necessary, you will be able to adjust masses, see the purity result for each multiplet (they should be similar), see the number of nuclides values and you will be able to change the analyte peaks to be included in the calculation. Once all is OK, click on OK and the report will be added to the spectrum page (if the applicable box was checked) :
After that, if you plan to work with a similar dataset, you can load the spectrum and re-run the 'Purity Calculator' script, selecting “Use parameters from previous calculation”. The only values you would need to change will be the masses.
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