Title:
NMR Manual for Solvent Suppressing on Agilent Spectrometers
Purpose
This manual will help NMR users understand an easy way to suppress the solvent peak(s) if they have one
or more huge proton peak(s) from solvent. Users should be able to easily follow the procedures to conduct
their experiments with little or even no NMR staff assistance.
Introduction
Sometimes, for some reasons, a user has to make an NMR samples by using a mixture of deuterium and
normal solvent. A typical example is 90% H2O and 10% D2O. In this case, the water peak will be huge
comparing to the other peaks from solute, with a normal H1 NMR experiment. Because the receiver gain
value is adjusted by the highest peak, the proton peak intensity from solute will be lost a lot. To a certain
extent, the proton peaks from solute may not be observed. Therefore, the solvent suppressing must be
applied, in order to obtain a decent H1 NMR spectrum.
The pulse sequence PRESAT is good for water suppressing, or for some other solvents which have only one
proton peak, such as acetone or benzene or chloroform. If there’s solvent which has more than one proton
peak, such as methanol (say 90% CH3OH and 10% CD3OD), another pulse sequence called WET should be
applied. In this manual, we use a water sample as an example to understand how it goes. The sample has 2
mM sucrose in 90% H2O and 10% D2O. In this case, a normal 1D H1 NMR would be hard to see the sucrose
peaks.
Preparation
Prerequisite: users have done the basic NMR training
Spectrometer: Any, but NMR-Hg400 and F500 recommended
NMR Sample Prep: We need deuterium for locking and shimming. The minimum deuterium solvent
depends on the solvent; e.g. 5% of D2O is OK, but 20% of CDCl3 or more is required.
A test sample, as example in this manual: 2 mM sucrose in 90% H2O and 10% D2O
Reading:



Agilent VnmrJ 3.2 Experiment Guide, page 44-52
http://129.105.219.103/nmr/vj_experiment_guide.pdf
http://www.chem.agilent.com/Library/technicaloverviews/Public/5991-4097EN.pdf
http://prdwww.lvld.agilent.com/Library/technicaloverviews/Public/si1849_onenmr_metabolomics_advn_v05_appd.pdf
Pulse Sequence of PRESAT:
Experiment Setup
1)
2)
3)
4)
5)
6)
7)
8)
Login on FOM system, then, login on spectrometer computer by netid
Insert NMR sample into magnet and do locking and shimming as usual
Run a regular 1D H1 (starting from exp1)
Change transmitter freq to the water peak; set cursor on the water peak, type nl movetof ga (Fig. 3B)
Setup PRESAT based on regular 1d H1 in exp2, by commands jexp2 mf(1,2) wft
Load PRESAT experiment into exp2 (Figure 1) and use default settings but change nt as required
Collect data and look at spectrum (you should have a similar one as Figure 3)
You may adjust parameter values of Delay or Power (Figure 2), if the water peak was suppressed too
much or too less, then, re-collect data
9) Save all the data (exp1 and exp2) into a correct folder
Figure 1. Experiment Selector Panel
Figure 2. PRESAT Parameters
B
A
Figure 3. 1D H1 spectra of Test sample A) with and B) without PRESAT
Ending Work
1) Switch a dummy sample into the magnet
2) Lock on CDCl3
3) Write a note on Log Book
4) Keep desk top clean
5) Logout from spectrometer computer and FOM
Manual Created by: IMSERC Lab, Department of Chemistry, Northwestern University
Manual Revised Date: March 2014