Welcome to the Temple Chemistry Department
Anasazi EFT-60 NMR Spectrometer!
Location:
Room 400,
Beury Hall
Caution: We
are using a
powerful
magnet!
Keep metal
away.
You must be
checked out
to use the
instrument
Magnet
Computer
Spectrometer
This procedure will require you
to use two different software
applications
The first is PNMR. This program runs the hardware and
measures the spectrum. It saves the raw data to the disk.
The second is NUTS. This is a data processing program.
You will pass data made by the PNMR program to the
NUTS program for processing and plotting.
The programs are both running on the PC and you can use
the menu bar to click back and forth between them.
Some Basics you need to know…..
Prepare samples
in a Deuterated
Top of magnet,
solvent at ca. 10%
with cover opened
w/v
Solvent volume
should be ca. 0.5
mL
A Properly filled
NMR sample tube,
0.5 mL volume
NMR tubes are
fragile, precision
cells. Handle
carefully!
Don’t drop the
spinner collar! If
dropped it will be
damaged.
Spinner collar
Sample
positioning guage
(view from front of magnet)
(hole toward
front)
A closer look into the magnet chamber…
This lever starts and
stops the spinning.
Leave in the On position
(shown)
Air Control
valves. Do not
adjust on your
own.
Sample Ejection
button
(view from right-hand side of magnet)
Entry port for
sample into probe
Changing
tubes, to
analyze
your
sample.
Here with
cover
open, we
retrieve
the sample
already in
the
magnet
Push and hold the sample ejection
button; the sample in the chamber
will rise up. Use other hand and
pick up by top of cell.
It is important to push the tube carefully into
the spinner collar
Then use the
positioning
gauge (hole) at
the front of the
magnet to
gently push the
cell down to
the proper
level.
This protects
the delicate
probe parts and
your sample
from smashing
into each other
•Using a tissue, wipe the outside of the sample tube. (getting
chemicals, dirt, grease etc. into the probe can degrade the
performance)
•Avoid touching the bottom surfaces of the spinner collar.
•Make sure that the spinner collar is in place.
•Make sure that the spinner collar is positioned correctly.
•Holding your sample by the upper part of the glass cell, let
your tube gently fall into the probe opening.
•Your sample will begin to spin inside the magnet. You can
verify this by ejecting and observing the motion of the tube.
Now close the plastic lid over the sample chamber.
•If the sample does not lower, pull the spin control lever up,
then push back down.
The computer
controls the
measurement.
You will find it
running a
program called
“PNMR”
PNMR has a
blue screen that
shows raw data.
Commands are
typed into the
text line (gray
box at bottom of
the blue screen)
Now, take a seat in front of the
computer workstation…..
The Data Acquisition Screen
You must
adjust the
NMR for your
sample. This
is called
“shimming”
At the
H1>prompt in
the gray line,
type:
shim<ret>
You will see a
box in the screen
asking for a time,
type in 5, then
click OK
Command line for typing in
commands
Now the Shimming Procedure takes over…….
Your see a display like
this one…
When finished, this
gray box disappears.
Starting your NMR measurement……
At the H1>
prompt on the
command
line, type
zg<ret>
You will first
get a file
naming box,
since the data
will be written
on the hard
drive. Enter a
filename, and
click Save.
Data Collection
Now your data
collection
begins. The
result is
displayed as a
decaying curve.
This is called a
FID (or free
induction decay)
or interferogram.
We can’t
interpret data in
this form, so it
needs to be
ported to another
program and
processed into a
usable form.
When the data
collection is
finished, mouse
down to the task bar
and click to the
NUTS application
How do I take a
13C
NMR?
13C
NMR is a little more challenging, since the
sensitivity compared to proton NMR is lower by a
factor of 6000.
We address this by:
Using more compound, and using no more volume
than needed (keeps concentration high)
Taking more scans
We load in the setup parameters for 13C at the prompt:
>nu C13
How much more compound?
About 100 mg of a organic compound of “normal”
molecular weight. (say <200 da) can be done in one
hour.
About 25 mg of the same compound will require
overnight data acquisition.
In either case, use sample volume of 0.5mL. Neat
liquids are OK, otherwise make up the volume so
that 0.5 mL of the nmr tube is filled. (about 1” high)
After you get the C13> prompt,
type “shim” (without quotes)
The parameters automatically change
back to 1H, and the trace on the screen
automatically responds as the shimming
is fixed. When the shimming is finished,
the gray box in upper right-hand part of
screen will disappear.
1H
Next, take a “quick and dirty”
NMR by typing zgh at the >C13
prompt.
When the scan is done, click into the NUTS window,
and type a2. This will display your proton spectrum.
You can check at this point to make sure the signals
come at their proper shifts.
In this
spectrum, we
see the water
peak has drifted
from its corrrect
position. This
needs to be
fixed.
Click back into
the PNMR
window.
Now if the shifts need to be
rescaled…type zo at the prompt.
Then in the
second dialog
box, enter the
correct
value…
In the first gray
window type the
current (wrong) line
position in ppm.
The z0 value on the screen
will update. Type zgh
again, then go to NUTS
Now in NUTS, type a2. Your spectrum
should be correctly positioned. You
might want to “save” the proton
spectrum at this point.
The new zo
number now
has water at its
proper
chemical shift.
Now go back to
the PNMR
application
The “Save As” dialog
will allow you to
direct the file to be
saved to your own
USB memory stick,
mounted in the
receptacle on the front
of the computer.
Taking a 13C spectrum
At the C13> prompt, type zg
As “zg” begins, the
program will ask if you
want to use “Broadband
Decoupling” This is the
preferred option, since it
will make each the carbon
signal into a single line.
(If we don’t turn on the
decoupling, the carbon
signals will be split into
multiplets from their
hydrogen neighbors.)
A box appears first, asking
you to type 1 (BB
decoupling) or 0 (no
decoupling) Enter a 1 in the
dialog box.
First the program asks how you want to save the
data file. The default is “PNMRFID”, but you
should point the Save to your own, e.g., USB
memory stick and make up a relevant name.
Our 13C spectrum begins to
acquire, by adding scans to the
memory
Taking a large number of scans
(for samples less than 50 mg)
Set up the 13C parameters as on
the earlier pages. However,
instead of typing zg, type bapr at
the C13> prompt.
This runs a macro that will take
a series of repetitive blocks of
data, and store on the disk. In
this example, we could type 10
into the box, and get 10 spectra,
each consisting of 64 scans.
We will use the NUTS software
to add these together. We can’t
just take 640 scans, because the
instrument’s magnetic field
drifts.
Dialog boxes will
also ask you to
select:
BB decoupling[1/0]
And shimming
between blocks [1/0]
Yes to both
questions
Also, you must
provide a file name
to save blocks into.
Data Processing
After
switching over
to the “NUTS”
application,
type at the >
prompt:
A2 (no enter
needed)
Your data will
display on the
screen as a
spectrum.
Plotting out the Data, and Finishing Up
At the > prompt in NUTS type >RU
A “File Open” dialog appears and you select a
macro called aii_H1_auto.mac, then click Open.
Now click OK in the dialog box that follows
Now your spectrum will print out, with the peak
areas integrated, and peak positions listed on the
printout.
Click/pulldown: FILE|SaveAs and save your
data in the folder on your own USB memory
stick (jump drive). Use a short descriptive name,
for future retrieval. Click Save,. File can be reread and expanded etc, using NUTS in 2nd floor
computer lab.
As an alternative, you may (as your instructor
may request) output the data for use with the
JCAMP viewer software. To do this you must
convert the file into JCAMP format, as shown,
and save the converted file to your folder. Note,
you must name the converted file with a .jdx or
.dx extension or the viewer will not recognize it.
Last, remove your sample as you did
originally, and replace the reference
sample into the spinner collar (has yellow
“CDCl3” solvent blank label)
You are finished, Congratulations!
If you chose the Block averaged method
for 13C, the PNMR program has created
a large number of “blocks” each of
which has a spectrum stored on the
disk. NUTS has to be told to handle this
kind of data in a slightly different
manner.
Processing the Blockaveraged data.
directions….
While Block 1 is running in PNMR,
switch to NUTS and type a2.
Use the Zoom tool, and isolate on a
single peak. Type the number 0.
This sets a peak that, for all the other
blocks will move a little to the right or
left so they are all lined up, and then the
adding of the blocks will work.
When all the blocks have completed, in
PNMR, switch to NUTS and type RU.
From the macro list, choose
aii_C13_bapr.mac | then, Open.
Then choose the name of the file you
saved the blocks into.
The data will appear as a single
trace, the result of adding up
several spectra.
You won’t see this
stack of noisy spectra..
80
blocks
of 64
scans
each