90° Pulse Calibrations


See instructions for performing a BioPack calibration.

You should check the pw90's and tof before starting a set of experiments, even though you have previously run the standard BioPack calibrations on a doubley labeled sample. This is described here.

tof Calibration (transmitter offset)


Load pulse sequence by typing “water” or selecting Menu -> Experiments -> WaterSuppression -> 1D -> PreSat
Select “Saturation” page and press “FindBestSaturationFrequency” button
For D2O samples you may need to abort experiment ("aa") and decrease satpwr and restart ("au")
This will array tof and satfrq to find the minimum water signal. Then it will run a 1H experiment allowing you to inspect the proton spectrum. Make a note of the tof (“Frequency”) value. You should use this tof for all your subsequent experiments to minimize the water signal. Optionally, you can enter this into your HCN probefile.

1H pulse calibration


Typical 1H pw90’s are 8 to 10 usec for BioPack sequences.
These are obtained using tpwr=53 on 500, and tpwr=58 on 800

hcch_tocsy
  • array pw and look for a maximum at pw90
gNhsqc
  • set calH=2.0
  • array pw about pw90 and look for a null in signal
  • reset calH=1.0 and pw=pw90
gChsqc - for samples in D2O
  • set calH=2.0 and array pw to find null at pw90
  • best to use only aromatic resonances, but use all if signal too low

15N pulse calibration


Typical values are 40-47 with pwNlvl=57 on 500, and pwNlvl=60 on 800

gNhsqc
  • set calN=2.0
  • array pwN about the expected value for pwN90 and look for a null in the signal
  • then reset calN=1.0 and set pwN to that found above.

ghn_co
  • if you need to calibrate pwN at lower power where pwN is too high for gNhsqc

13C pulse calibration


Set pwClvl=60 on 500; set pwClvl=61 on 800

gChsqc
  • set calH=2.0 and array pw to find null at pw90
  • best to use only aromatic resonances, but use all if signal too low
  • typical values are 14 on 500 and 13 on 800