Concentration Workflow

Generally, the workflow will be:

•Determine multiplets

•Run the script and select the qNMR variables

•The software will choose the multiplets to include

•Report

So first of all, we will load a 1H NMR spectrum and apply the necessary processing. (Depending on the level of accuracy required, you must pay attention to the number of data points used for the FT (typically 64K) and to apply a phase correction. Sometimes a baseline correction could be also needed. If necessary (e.g., solvent saturation was used), blind regions should be used to mask these spectral regions).

In the example shown below (which you can download from here), we have just loaded the dataset and applied an 'automatic multiplet analysis':

The qNMR functionality is selected from the “Quantitation” menu item. The software stores all settings in the registry, so you may not have to change things. But you will need to provide some information the first time you use this. This will be described in more detail, below. For this tutorial, we have clicked on the ‘Settings’ button of the qNMR panel and then on the ‘Load Parameters’ button to load the ‘1_acetanilide.data’ file (which you have downloaded together with the dataset in the previous step):

After having clicked on the OK button, the qNMR panel will be displayed with the information about the multiplets and compensated integrals found for their bounds. Having the correct number of nuclides is important and the software may do this better if the molecular structure is available and plotted.

Click on the Calculate button to run the concentration analysis. At this stage the qNMR process will be done automatically and the multiplets sorted in the table based on their perceived ranking as candidates for qNMR. The selected multiplets can be changed using the check boxes next to each multiplet, and the effect on the derived concentration will be updated. The concentration averaged calculated for this example is 21.5 mM (the units can be changed by using the applicable combobox)

You will find different button in the qNMR panel above:

1. Report qNMR results on the spectrum page, export the report into a txt file or copy the report to the clipboard (depending on the report options that you have selected in the settings)

2. Show the “Settings” dialogues

3.Selects best multiplets based on rules (see qNMR Settings)

4. Select all/no multiplets. (An alternative to 3)

5.Normalize the number of protons

The user can check the applicable boxes to manually select/deselect the multiplets that will be used to calculate the concentration information. The “Hs” for a multiplet can be manually changed by clicking on the number.