High temperature calibration

When you perform a Variable Temperature (VT) NMR experiment, the displayed temperature is not necessarily the actual sample temperature.  When you need to know the actual temperature, with a high degree of accuracy,  it is important to calibrate the sample temperature, relative to the displayed temperature.

The common method to perform this calibration is to observe the chemical-shift separation between the OH resonances and CHn resonances in either Methanol or Ethylene Glycol (generally Methanol is used for low-temperature calibration, and Ethylene Glycol is used for temperatures above ambient).  The temperature dependence of this shift has been well-studied, and a variety of conversion methods have been reported to enable the determination of sample temperature.

You can dowanload this  xls file (nmr-tempcal), which allows easy determination of either (a) temperature from measured shift separation, or (b) predicition of peak shifts for a particular temperature (created by Rich Shoemaker). The use of this spreadsheet is simple.  There are fields to enter temperature (calculating the chemical shift separation), and fields to enter peak-separation (calculating the temperature).  A variety of solvent systems are included.

REF: Link

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