How to Set Up Solvent Suppression

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1. Set up your solvent suppression standard file (you only need to do this once).

(a) create a blank file from any template. Name it something like “standard-watersup”

(b) type rpar, select “…/user” directory, then select “ZGPR1”. Click OK on the window that subsequently pops up.

(c) type getprosol to complete setup. (you could also complete steps (b) and (c) by checking appropriate boxes in the edc window).

 

2. Find the frequency of the solvent (most frequently water) peak. You will need to do this every time you run a solvent suppression experiment. Water suppression only works when the frequency of your pulses is exactly on the water peak.

(a) run a regular proton spectrum;

(b) zoom in your solvent peak on the screen;

(c) click this button (set RF by cursor):

watersup-2

(d) left click on solvent peak top, and the following window will pop up. Write down the frequency shown in the pink blank:

watersup-1

(e) click Cancel.

 

3. Run experiment.

(a) create a new file from your standard water suppression file;

(b) type o1 (o stands for offset), enter the value you recorded in Step 2.

(c) run your expt like you do any other NMR expt (rga, zg).

(d) use manual phase correction as apk often has a hard time dealing with the somewhat distorted water peak. phase it such that your solute peaks are correctly phased, which might mean that the solvent peak has to be left out of phase. This will be addressed in the next step.

4. Optimization

(a) display a spectrum range of ca. 1 ppm wide with the solvent peak roughly in the middle. Type dpl1. This defines the spectral range that will be displayed during parameter optimization.

(b) type paropt (which stands for parameter optimization). You will be asked several questions: (1) parameter to optimize. enter o1. (2) beginning value. e.g. if the o1 determined in the last step was 2350Hz, enter 2345. (3) increment. enter 1. (4) number of experiments. enter 11. This will run 11 experiments with o1 ranging from 2345 to 2355.

(c) tighten the paropt step size and find the best solvent suppression. When the suppression is best, the out-of-phase water peak problem will be minimized. You might have to use 0.01 Hz step size to find the best suppression.