Nuclear Magnetic Resonance (NMR)
Purpose:
This lab is meant to give us multiple days to work with and familiarize ourselves with the
NMR. During these lab periods we will learn the correct operating procedures for the instrument by
making and running samples, which include different oils and acids they contain, and interpreting
the results. We will also be running an unknown to see what we can determine from the results.
Overall we hope to have a much better understanding on how to properly use the NMR and to then
help others use the instrument.
Introduction:
Nuclear Magnetic Resonance Spectroscopy is typically used to determine structures of
organic compounds. Placing a desired sample in a very strong magnetic field does this. The nuclei
affected by the field can then be interpreted. Most common nuclei are H and C. NMR is commonly
used because it is non-destructive. Because of the strong magnetic field produced by the NMR
different molecules will react uniquely because they have their own magnetic field produced by the
movement of their nuclei and electrons. High frequency electromagnetic radiation stimulates the
molecule and it will react specifically based on its structure and chemical properties. Then there is a
detector to measure the electromagnetic radiation that results. By use of a computer software the
two signals can be compared and the difference from the time domain can be converted. NMR
spectroscopy helps one identify and count unique carbons and protons. The isotope must have a
spin factor of positive or negative ½ in order to scan for different isotopes. 1H and 13C are the most
common scans.
Procedure:
-Making a sample
 In an test tube mix 4 drops of sample if liquid with approx 1.5mL of desired solvent
o For a solid use about a spatula tipfull of analyte (85mg)
 Then fill an NMR tube approx. 4-4.5cm full
 Make sure to cap and label the NMR tube
 Transfer the tube in an 125mL Erlenmeyer flask
-Using the Instrument
 Open “YCP Chemistry” and click on Topspin program
 Type “ej” to eject the place holder
 Wipe your NMR tube with a kimwipe and place in the blue holder in the wooden
block
 Place the prepared NMR tube on the feeder then type “ij” to inject the sample
 Type “ro on” this starts the rotation of the sample
 Type “new” to input the experiment parameters
 Select the proper solvent and experiment type
 Type “rsh” to select a shim file and type “lock” to lock the magnet
 Type “bsmsdisp” to begin the shimming program
 Only adjust the z and z2 to adjust the shim
 Then type “ft” to Fourier Transform the spectrum
 Type “apk” to choose your peaks
 Type “abs” in order to adjust your baseline
 Print the spectra
 Type “ro off” to stop the spinning” and then type “lock off” and “ej” to eject the
sample
 Type “ij” to inject the place holder
Data: All spectras are placed in the lab notebook so refer there for all data.
Results:
During the course of the lab I ran 1H and 13C on olive oil, vegetable oil, peanut oil, and
unknown A. Along with these oils I also ran analysis on three acids, which include oleic, palmitic,
and stearic. All of these spectras can be found in my notebook. Also I completed a 2D on unknown
A. The acids were analyzed in order to determine which acids could be found in which oils. When
looking at the spectras it is clear that olive oil is made up of all three acids. Peanut oil contains both
palmitic and oleic acid. Vegetable oil similar to olive oil contains all three acids, but in different
quantities. When looking at the spectra for Unknown it appears to be identical to that of peanut oil.
There is the same number of peaks at the same place just observed at different intensities. All of the
acids are made up of long carbon chains with a carboxyl group at the end. Also oleic acid has a
double bond where the other two acids only consist of single bonds.
Conclusion:
The NMR is an extremely useful instrument for many different studies and is easy to use. It
is important to know about the analyte you are trying to analyze so you can use the proper solvent
and have an idea of the number of peaks you should expect to see. In this lab we used the NMR to
analyze the composition of three different common cooking oils. It was interesting to analyze the
structures found in these common oils. I feel it is extremely important to be familiar with using the
NMR because it has so many uses. This is shown by the number of students at the college that use it
whether it be for classes like instrumental, physical chemistry II, and organic II or for different
independent studies.