Temperature calibration with ethylene glycol.

• Use edte to set the temperature given best available information to achieve the true temperature at which you wish to operate.
• Load the sample and leave some time for equilibration.
• Turn SWEEP off.  There is no deuterium upon which to operate a lock, and the frequency shifts that are part of the lock operation will interfere with this spectrum.
• Shim the sample by maximizing integrated fid. This methods does not require the deuterium lock signal.  It may also be a good method for improving higher order shims on proteins samples, sincethe integrated area of the fid may be more sensitive to improvements in these shims than is the lock signal.
• Read (rsh) a suitable wilmad shim file, eg. aph_dss_wilmad.
• If you haven't already set up a specialized dataset for the dss calibration, do so now by selecting calib1h and using edc to save it by a different name, eg. oned_ethgly.xxx.
• Make TD (total data points) to 8K. This high value will increase the resolution by taking more data points.
• The exact settings for the 90 degree pulse width and the shimming are not particularly critical.
• Use gs and acqu to display a continuously acquired fid.
• Noting the integrated fid value displayed in the info window, adjust the shims in the usual order to maximize this value.
• Type stop to end the continuous acquisitions when your are through shimming.
• Tune and match the proton probe as usual.
• Measure the chemical shift between the two peaks in the ethylene glycol spectrum.
• Take the spectrum (zg), fourier transform (ef), and phase.
• Set the right peak to 0.
• To zoom on the peak, left click to associate cursor with the spectrum (the cursor will seem to stick to the spectrum). Then middle click to the left and the right of the peak to zoom in on it.
• Click on <calibrate> and put the cursor at the peak tip and middle click. This will open a box into which to enter a 0.
• Zoom on the left peak in the same way, and position the cursor at the peak top.  Read the chemical shift from the information box.
• For 100% ethylene glycol, y = 4.5677 - 0.0097723 x, where x is temp. in Kelvin. and y is the chemical shift.
• If necessary, reset the temperature to get the desired true temperature given the measured bias. Leave some time for equilibration.
• Take several readings with some time in between to be sure that the sample is thermally equilibrated.  The thermistor comes to equilibrium before the sample does.