Automatic NMR operation procedure (lignin analysis)
Sample preparation
1. Preparing internal standard: 50.33 mg/mL TMB (trimethoxylbenzen) in DMSO-d6
2. Add 100 mg Organosolv lignin (Oven Dried) and 20 uL TMB solution into 0.75 mL DMSO-d6
3. Vortex or Vibrate for 5 minutes until completely dissolved and transfer the solution into a 5 mm NMR tube.
NMR Spectroscopy
4. Log in to VNMRj, Setting for the first time. Click “Edit” ->”Preferences” , Click “Queue” button in “Preferences” window, de-select “AutoLock” “AutoShim”, Click “Save” below and close the window.
5. To eject the previous sample tube, input “e” in command prompt (right middle) or click “Eject” button in the parameters panel (right bottom)
6. Load the new sample tube in the spinner and adjust the height by tube meter, then put on the top hole of the spectrometer
7. To insert new tube, input “i” in the command prompt or click “Insert” button in the parameters panel
8. Tune the probe
a) Type “mtune” at the command prompt
b) The tune scree should appear
c) Select Channel 1 for proton and Channel 2 for C13
d) Start probe tune by turning inputs at bottom of instrument, after choosing “start probe tune” and clicking “Autoscale” button. Left is H1 (proton) and Right is H2 (Carbon).
e) When finished, select “Stop tune”
f) Select C13 and repeat
9. Click “New Study” button in the Study Queue panel (Left bottom), it creates a “SampleInfo”
strip in this panel
10. Parameter panel shows “Start” in active (Left column), Click “Standard”, input sample name, and any other additional information in each box. Select solvent, here in” DMSO”
11. Click “Lock” (left column of parameter panel), and click “Find z0” (right section), when it finish, the message window shows
“ Finding z0
exp1: Experiment started
exp1: Acquisition complete
Set hardware: operation complete
z0 set to 3039
Set hardware: operation complete”
12. Click “Shim” (left column of parameter panel), click “Gradient Shim” to optimize shimming. The shimming strategy is the same as what we used to have. Note, this panel is also in charge of checking and controlling Spin, Temperature and Air flow.
13. After Lock and Shimming done, move the mouse to “Experiment Selector” panel (Left upper). There are a few options “Common” “Liquids” “Calibration” “Service”
14. Click “Common”, and Click “Proton”, PROTON_001 is added in Submit Queue (Study Queue) panel.
15. Double click PROTON_001, “Acquire” is active in parameters panel, feel free to edit the acquisition parameters
For lignin sample, Receiver gain 18, spectral width -2.0-14.0 ppm, number of scan 8, relaxation delay 1.0 s, Pulse angel 30, pw90 13.5 s
16. Move back to “Experiment Selector” panel, click “Liquids”, and click “Sel2D” and choose “(HC)bsgHSQCAD” for 2D-HSQC analysis of lignin.
17. (HC)bsgHSQCAD_001 is added in the submit queue, double click (HC)bsgHSQCAD_001, “Acquire” is active in parameters panel, edit the parameters accordingly. \
For lignin sample, c13 spectral width -10.0-210.0 ppm, Scans/Increment 32, t1 increments 512, one-bond J1(CH) 147/150Hz, Receiver Gain 50, Relaxation delay 1.5 s, Observe Pulse at power 13.5 s