Thanks for all responses to my question about water suppression using
decoupler on the VXR 300. Here are suggections I have got:
1) Use s2pul sequence, set dof=tof where dof= water resonance, dm='nyn'
dhp=20-40, d2=1-3s.
2) Use the jump-return sequence or 1331 type non-excitation pulses.
Both suggestions worked. However, the first one only works when water is
about 10% in the sample. With a large amount of water (90%) in the sample,
it is very easy to get ADC overflow even in the low dhp (25) and minimum
gain (0). I suppose it may due to the limit of dynamic range of the VXR
300. Method 2) workds for both 10% and 90% H2O samples.
Thanks again!
Qing Ning
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Qing Ning, Ph.D
NMR Specialist Analytical Service Lab
q-ning@nwu.edu Department of Chemistry
tel. 847-491-7080 Northwestern University
Fax 847-491-7713 2145 Sheridan Road
Evanston, IL 60208