nmr service what equipment do we have? what can it do? how do you get to use it? where can you find...
TRANSCRIPT
NMR Service• What equipment do we have?
• What can it do?
• How do you get to use it?
• Where can you find it?
• Other stuff you need to know.
What Equipment do we have?
• Bruker AC200
• What can it do?
Open-Access instrument with Sample Changer
1H at 200MHz, 13C at 50.3MHz1H, 13C and DEPT, routine work only
• How do you get to use it?
User operated - Very easy - 10min training
No booking - first come, first served
What Equipment do we have?• Bruker DPX400
• What can it do?1H at 400MHz, 13C at 100.6MHz, etc, etc…
Multinuclear, 2D, Pulsed Field Gradients
Variable Temperature, Non-routine work
• How do you get to use it?
Operator instrument
Job Request Forms
Time is bookable
Where can you find it?
•Ground floor
•Spur building
Where can you find it?
•AC200 in G21 (left)
•DPX400 in G20 (right)
NMR Service Charges
• Your supervisor pays a real money fee for
every NMR Job done.
• Each Job done on the AC200 costs £1.
• Each Job done on the DPX400 costs £1.
• The money pays for the running costs of the
NMR service, e.g. cryogens, paper, repairs,
etc.
NMR Service Charges
• You must tell me your Job Number or
Account Code.
• If you don’t work in Chemistry you
must also tell me your Cost Centre.
• Your supervisor has this information.
What else do you need to know?• AC200 Training
Done by me when you bring your first sample Takes about 10-15 minutes.• NMR Work Request Form
Required for all DPX400 work.Makes sure your work is not forgotten.You must provide a sample or make a booking.
• NMR Data ArchiveEverything is kept forever, so that you may
reprint data yourself.• How to Prepare NMR Samples
Leaflet - PLEASE READ IT!
NMR Work Request Form
• Identifies you and your sample.
• Describes your sample (Quantity, structure, solvent, hazards).
• Outlines the work you want done, or the information you need from the spectra.
NMR Work Request Form
NMR Work Request Form
NMR Data Archive• All data is archived and kept for ever so that you can do
expansions and reprints for theses, papers and posters.
• Data is always available by FTP from our own server.
• It is stored in folders by years, months and finally by user. Each instrument has its own archive.
• Dozens of people use the NMR service, hundreds if you look back over the years.
• So that you should always be able to find your data, we enforce a strict data naming convention.
Data Naming Convention• User Code
Given to you when you register
Three letters, or two letters and a number
• NucleusElement symbol: H, C, B, P, etc
• Sample CodeUp to four characters, your choice, A-Z, 0-9
No lower case (a-z) or punctuation marks
Don’t include your initials, or ‘EXP’ or ‘RN’
• Extension or ‘expno’ - experiment numberAdded by the system to indicate the type of work
Data Naming Convention
• AC200 File Name:
aaabcccc.ddd
Data Naming Convention
• AC200 File Name:
aaabcccc.ddd
User Code
Data Naming Convention
• AC200 File Name:
aaabcccc.ddd
User Code
Nucleus
Data Naming Convention
• AC200 File Name:
aaabcccc.ddd
User Code
Nucleus Sample Code
Data Naming Convention
• AC200 File Name:
aaabcccc.ddd
User Code
Nucleus Sample Code
Extension
ASBH456.001
(AC200)
asbh456a 1 1
(DPX400)
NMR Data Archive
• Machine address: dava.eps.hw.ac.uk
• Login name: nmrftp
• Password: nmrftp
• Path: / - the top
level
How to Prepare Samples for NMR
•In NMR, unlike other types of spectroscopy, the quality of the
sample has a profound effect on the quality of the resulting
spectrum.
•If you follow a few simple rules, the sample you prepare will
give a spectrum in which useful information is not lost or
obscured.
Use the Correct Quantity of Material
•For 1H spectra of organic compounds (except polymers) the
quantity of material required is about 5 to 25mg.
•13C is six thousand times less sensitive than 1H. If you can
dissolve about 0.2 to 0.3 millimole in 0.7ml, the spectrum will
take no more than about half an hour to record on the AC200.
•On the DPX400, 0.1 millimole gives a fair 13C spectrum after
less than an hour.
Signal-to-Noise Ratio
S/N
S/N NS
S/N m
Where NS = number of scans, m = number of moles of sample
So How Long Will it Take?
NS Time Relative S/N
256 15 min. 1
1,000 1 hr (over lunch) 2
4,000 4 hr (half day) 4
16,000 16 hr (overnight) 8
64,000 64 hr (all weekend) 16
NS = number of scans for a standard 1H-decoupled 13C spectrum.
For other experiments, compare relative times only.
Remove All Solid Particles
• Solid particles distort the magnetic field homogeneity
because the magnetic susceptibility of a particle is
different from that of the solution.
• You must remove solid particles from your samples.
• Filter ALL solutions into the NMR tube through a small
plug of glass wool tightly packed into a Pasteur pipette.
Make Samples to the Correct Depth• In the magnet, the main field direction is vertical, along the length of the
sample. Each end of the sample causes a major distortion of the field
homogeneity which is corrected using the spectrometer’s shim controls
• A partial correction is done for every sample, and takes a few minutes. A
complete correction takes many hours using a high quality test sample.
• Your samples must be prepared so that they physically resemble the test sample
so, after filtration, they must be made up to a similar depth. This must be
between 5cm and 5.5cm, and requires about 0.6 to 0.7ml solvent.
• Shorter samples are very difficult to shim, and cause considerable delay in
recording the spectrum. Samples that are too long are also difficult to shim and
are a waste of costly solvent
B0
Clean your NMR Tubes!
• This cleaning device is cheap and easy to set up
and use.
• Use pipecleaner for stubborn stains.
• Dry tubes with a blast of dry nitrogen or air.
• NEVER dry tubes in an oven - it doesn’t work
and tubes may distort in the heat.
• Don’t forget to clean the tube caps too!
Damaged NMR Tubes
Mend Damaged NMR Tubes
Good Sample Containers
Bad Sample Containers
Things We Love To Hear!1. It’s 100% pure, only one spot on TLC.
2. What exactly is broad-band decoupling / COSY / VT /etc?
3. Do you think you could get it to run me off a few integrals?
4. Well, it dissolved perfectly OK in the chloroform in the lab.
5. Could I book a few days for some VT work?
6. I don’t think I actually know what you mean by “overwrite”.
7. Don’t be silly, of course there’s a signal there.
8. What do you mean by an expansion?
9. Why have you changed the signal-to-noise ratio of this spectrum?
Things We Love To Hear!10. The coupling from H1 to H2 is 4.93 Hz, but the coupling
from H2 to H1 is only 4.20 Hz.
11. Oh, that’s the solvent is it?
12. You remember that sample you did for me, about two weeks ago?
13. Gosh, that did take a long time!
Actually, I’ve got loads more of this stuff if you’d like it.
14. Could you plot this out as a DEPT please?
15. Could you do a DEPT for me on this 1H spectrum, please?
16. I’d like a DEPT just over this small region here please.
