IMSERC NMR Written Certification Test (A) Name: ____________________
Date: ____________________
YOU MUST GET ALL OF THESE CORRECT (questions 1-10):
1) Which metals are dangerous to bring next to the magnet (circle them)?
Aluminum
Iron
Surgical stainless steel
gold
Platinum
copper
steel
titanium
nickel
silver
2) What should you do if you break an NMR sample outside a magnet?
3) What should you do if you break an NMR sample inside a magnet?
4) Situation: You click “eject” to eject a sample, and the air turns on but no sample comes out.
What should you do?
5) What is “locking” and why do you do it?
6) We often describe spectrum quality using the term “linewidth”. What does that mean, and what
is a good linewidth for a routine sample? Please sketch.
7) Explain what is going on inside the magnet when you are shimming.
8) What is the minimum volume of sample required to achieve a good signal from a sample in a
standard 5mm-diameter tube? Circle one: 0.2 mL, 0.5 mL, 1.0 mL?
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IMSERC NMR Written Certification Test (A) Name: ____________________
Date: ____________________
9) Situation: You took a 16-scan spectrum with a poor signal-to-noise ratio, and now you want to
improve your S/N by a factor of 4. How many scans to you need?
10) NMR spectrometers are equipped to spin samples, but we don’t do this in IMSERC. Why do
we not spin samples here?
YOU MUST GET 7 OF THE FOLLOWING 12 CORRECT:
11) What nucleus do we normally use for “locking”? Why?
12) On a “500 MHz” NMR system,
a. The 1H nuclei resonate at ___________ MHz
b. The 13C nuclei resonate at ___________ MHz
13) Situation: You acquired 1H and 13C 1D spectra, but you cannot easily assign your peaks. Which
two easy, short 2D spectra should use for help?
14) Briefly describe the major problem with this spectrum. Is it a data acquisition problem or a
processing problem? What do you do to fix it?
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IMSERC NMR Written Certification Test (A) Name: ____________________
Date: ____________________
15) Which are suitable sample concentrations for routine 1H data acquisition on a ~500 g/mol
compound on an IMSERC Varian walkup instrument? (Circle answers)
0.01 mg/mL 0.1 mg/mL
1.0 mg/mL
10 mg/mL
100 mg/mL
16) 2D spectroscopy: What is the difference between “nt”, the number of transients, and “ni”, the
number of increments?
17) What is “zero-filling” and why do you do it?
18) You acquire a spectrum and all the peaks are there, but the PPM values of your peaks are
wrong. What is the most likely cause of the problem, and how do you fix it without acquiring a
new spectrum?
19) You acquire a quick 16-scan 1H spectrum that gives you OK signals, but your integral values
don’t make sense. What single acquisition parameter must you adjust so you can acquire data
that give you good integrals?
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IMSERC NMR Written Certification Test (A) Name: ____________________
Date: ____________________
20) NMR tubes are best dried with a stream of dry N2. However, one can use an oven for drying
NMR tubes if:
a. The oven temp doesn’t get above __________ °C
b. Choose one: You lay the tubes flat on their sides / You put them upright in a flask
21) What happens to your data if your sample does not have sufficient volume, even if it is very
concentrated?
22) Situation: you’ve established lock, but your lock level is bouncing up and down. What is the
parameter you have most likely mis-set? Should it be set higher or lower?
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