All potential users MUST be accompanied by (1) a TA or (2) a qualified user
(determined by A. F. Miller and/or John Layton).
Instructions for Use: 1H NMR on Varian Instrument
1.
Log onto the machine. This requires a username and password. You may
use this instrument ONLY with the assistance of a trained user. More
information can be provided by them.
2.
Eject the sample that is in the machine and put your sample in. Your TA
will explain how to do this.
3.
Your TA or John Layton can log you in. If you don't see an open window
with a big black empty space click on VNMR in the long window at the
bottom of the screen to open up the VNMR program. If you don't even
have that, try double clicking an icon or two to see if you can open one of
these two windows.
4.
Click on the Setup button and choose an appropriate nucleus and solvent.
For example, for a proton spectrum in chloroform click on the H1,CDCl3
button, or for a proton spectrum in benzene click on Nucleus,Solvent
followed by H1 and Benzene.
5.
Click on the Acqi button which will open up a smaller new window titled
'gembb.chem.uky.edu ACQUISITION'.
6.
Click on the Lock button. You will be presented with the deuterium lock
signal. If the spectrometer has locked onto the signal the trace should look
like a flat step function and the lock level will be fairly constant and above
30. If it is not locked, try raising the lockpower and or lockgain. The
controls for this work just like the shim controls (see below). If that doesn't
work, close the window. Type rts(solvent) su (where solvent = your
solvent such as cdcl3, c6d6, toluene etc.) and start again from the
previous step . If you still don't get a lock, ask for assistance.
7.
Shimming" means that we are simply adjusting the magnetic field inside
the instrument to be as homogeneous as possible. To shim the field, click
on the Shim button. You'll see two horizontal bar graphs that show the
lock level. The bar on the top is a tens unit and the one on the bottom is a
ones unit. The same information is also displayed more simply as a
number.
(a)
Below this display next to the word 'Shim' there is a small
triangle that switches between different lists of shimming
parameters when you click on it with the left mouse button.
You do not need to adjust all the parameters, just those
listed below.
8.
(b)
To adjust a value, simply click on the buttons labeled -1+, 4+, -16+ and -64+. Think of these as fine through coarse
controls; clicking on -16+ changes the value 16 times as
much as clicking on -1+. If you click with the left mouse
button you decrement the value of that parameter and if you
click with the right mouse button you increase the value of
the parameter.
(c)
Shimming is accomplished by adjusting each shim
parameter to maximize lock level. It is not the absolute
number we care about (these can always be changed using
the power and gain), rather we want to get the highest level
we can while having the bars (lock level) read on scale.
To shim the instrument simply:
(a)
Make sure your lock level reads on scale as described above.
(b)
Adjust the Z1C (z1 coarse) and Z2C (z2 coarse) buttons to
shim. You shouldn't need to use more than -1+ or -4+ to do
this. Maximize the reading on the scale using Z1C and then
do the same using Z2C. Iterate this procedure back and forth
until you can not get the bars/numbers to go any higher. If the
lock level pegs at the top of the scale, reduce the lockpower
and/or lockgain until the meter again reads mid-scale (you'll
need to toggle through the parameter list to see these
parameters).
(c)
Use the Z1 and Z2 controls to finish shimming (these are
about 5x less sensitive than the coarse controls). Normally all
you need to use is the -16+ button.
(d)
Now maximize the lockphase (you'll need to toggle through
the paramter list to see this parameter).
(e)
Click on the Close button to exit the Acquisition window. Do
not attempt to adjust the other shims such as Z0, Z3, Z4 etc.
(f)
Click on the Close button to exit the Acquisition window. Do
not attempt to adjust the other shims such as Z0, Z3, Z4 etc.
9.
Click on the top window, type nt=4 and hit return. This sets the number of
scans to 4. We're going to make sure that our peaks look OK before
collecting a full set of data.
10.
Type su ga. The spectrometer will collect 4 scans and then display your
spectrum (see below on how to manipulate things). Adjust the phase by
typing aph and make sure that your peaks look good -- they should be
Gaussian in shape and not have humps to either side. Typical problems
with shims will give humps or even extra peaks on the side of your real
peaks. Fortunately, this problem will show up in all of the peaks of your
spectrum, so they are easy to spot.
(a)
If you suspect your peaks are misshapen due to a bad shim,
go back and try shimming again. If this still does not help type
try using the rts command described above. The rts
command ("return to shims") loads in a set of values that
should be close to the values that you need for a particular
solvent.
(b)
If you are still not having any luck, ask your TA or John
Layton for help. There is a manual phase adjustment, but its
use is too complicated to explain here.
11.
If everything looks good, decide how many scans (transients) you want to
collect. For example, to collect 16 scans and begin acquisition type nt=16
ga.
12.
While your scans are collecting, it is a convenient time to enter text about
your sample. Type text('your sample information here'). Don't forget the
single quotes and parentheses. Use a double backslash to begin a new
line.
For example:
text('RTI-155A, Crude product from\\ether/pentane, orange
oil\\yellow C6D6 solution\\8:55P 09-10-98') will produce:
RTI-155A, Crude product from
ether/pentane, orange oil
yellow C6D6 solution
8:55P 09-10-98
13.
When your scan is done type aph f to automatically phase your spectrum
and display the full spectrum.
14.
There is a button that toggles between Cursor and Box. Click the left and
right mouse buttons to get two cursors. Place these on either side of your
residual protio solvent peak and then click on the Expand button. Place
one cursor on the center of this peak and type nl rl(x.xxp) where x.xx is a
number you need to supply. A list of residual solvent shifts can be found
be the spectrometer. Typical values are 7.24p for CDCl3 and 7.15p for
C6D6. Do not forget the lowercase "p".
15.
Click on the Full button to display the full plot. Use the two cursors to
expand the area you wish to plot. Alternatively, you can type in something
such as sp=0p wp=8p to display, for example, 0 to 8 ppm automatically.
Typing in the values ensures you can plot all your spectra on the same
scale and overlay them for easy comparison later. To change the vertical
scale click and drag on the spectrum with the middle mouse button. Make
sure all your peaks are as high as they can be without being cut off at the
top. You can also set the value of the vertical scale, for example vs=200.
16.
To integrate your spectrum find the button that toggles between No
Integral, Part Integral and Full Integral. Select Part Integral to
automatically integrate and type cz dc to automatically clear any integral
resets and level your baseline.
17.
Click the Resets button and then cut (zero) your integrals as needed.
Working from left to right, move the mouse and click the left mouse button
once where you want the integral to be cut. If you make a mistake the right
mouse button undoes a cut (or you can use the cz command to wipe all
the cuts). Adjust the height of the integrals by clicking and dragging with
the middle mouse button when you are done. Make sure the integrals are
as tall as possible without being cut off at the top of the page.
18.
To plot your spectrum type pl pscale hpa which plots the spectrum, scale
and parameters, respectively. If you are not going to do inset plots, type
page to dump the spooled file to the plotter.
19.
To generate a peak list first toggle through the Integrals button to get rid
of your integrals and then press the Th (horizontal threshold) button. Click
and drag with the left mouse button to set the height of the peak list
threshold. Pick a level that intersects all your peaks of interest, but don't
put it so low that it picks off every single point in the baseline. Then type
printon dll printoff to send the peak list to the printer.
(dll will list only those peaks that are displayed on the screen and that are
above the threshold. For complex spectra it may help to expand several
regions and dll them individually).
20.
When you are finished, remove your sample and replace the one that was
in the machine when you got there. NEVER PLACE THE SPINNER
BACK INTO THE INSTRUMENT WITHOUT A SAMPLE.
21.
Log off the instrument by typing exit. A confirmation message will come
up. Click OK or hit return to finish logging out.