SUMMARY

A new manual and corresponding video are presented that show how to use Topspin 3 to process and analyze T₁ relaxation measurement data to extract T₁ values. The illustrations correspond to ¹H data, but can be applied to normal pseudo-2D T₁ data for other nuclei. This does NOT cover data acquisition – just analysis.

MANUAL: https://bpb-us-w2.wpmucdn.com/voices.uchicago.edu/dist/0/2147/files/2025/05/T1measurement_1H_2D_TS3_2025-0523.pdf
VIDEO: https://www.youtube.com/watch?v=gAdC_n_pryo

MOTIVATION

The accuracy of all quantitative NMR methods, including simple integration, relies on full relaxation of all analyzed spins between scans. Your D1 relaxation delay value should generally be set to approximately FIVE times the longest T₁ of interest, but to do that you must know your T₁ values. Experiments using 30° excitation pulses, like PROTON8 and normal CARBON, get by OK with shorter D1 delays, but one should still base the D1 setting on one’s longest T₁ to be quantitative. You may acquire data automatically, but you must process it manually. Here is the preferred UChicago processing method using Topspin version 3.

THE INVERSION-RECOVERY EXPERIMENT FOR T1 MEASUREMENT

Figure in two parts. Top part shows the inversion-recovery pulse sequence, featuring the variable D7 recovery delay. Bottom part shows a set of 3D axes with bold vectors on them corresponding to net magnetization; this part shows how net magnetization is inverted by the 180-degree pulse, recovers to different extents during the D7 recovery delay, rotates into the X-Y plane with the 90-degree pulse, and is acquired at the end. Fourier transformation provides peaks with intensities that grow from negative to positive as D7 is lengthened.

EXPERIMENT DESCRIPTION

With all spins fully relaxed along the +Z axis, a 180° pulse (“inversion”) is applied, aligning them along -Z. In the recovery period, they relax so their intensities gradually return to the +Z axis. The signs and intensities of their magnetizations at the end of recovery depend on the length of the recovery delay, D7, AND the rate of relaxation, R₁ (1/T₁). A 90° pulse is then applied to put the magnetizations in the X-Y plane, where they can be observed. Data are acquired with a small array of D7 values, and after Fourier transform, spectra are phased so the spectrum with the smallest D7 has negative peaks, and the one with largest D7 has positive peaks. Integrals of all peaks of interest are plotted as a function of D7, then fitted to obtain the T₁ relaxation times of all integrated peaks.

Results from T₁ analysis performed using Topspin 3 on the ¹H signals from carvone. The plot of Intensity-vs-D7 delay time for residual solvent CHCl₃ is shown. Peaks with short D7 durations have negative intensity and grow to positive intensity as D7 lengthens.

SUMMARY OF STEPS TO PROCESS DATA AND MAKE MEASUREMENTS

1. Open the t1ir dataset and check the number of FIDs
2. Perform Fourier transform in the F2 dimension
3. Perform manual 2D phase correction in F2
4. Perform automatic baseline correction in F2
5. Calibrate/reference your chemical shifts
6. Use the T1/T2 analysis tool to measure T₁ values
   1. Select the last spectrum in the series (longest D7)
   2. Define integral regions manually
   3. Enter the Relaxation Window and confirm Relaxation parameters
   4. Check “Fitting”, parameters, specify “Area” for measurement
   5. Perform the data fitting with the Calculate tools
   6. Check T₁ values for reasonableness, inspect quality of data fitting
7. Generate a report and save it as a text file

NOTE ON TOPSPIN 4:

The manual and video provided here used Topspin version 3. The same method will work for Topspin version 4 EXCEPT that the T1/T2 analysis tool is found in the Applications…Dynamics menu in version 4.

Screenshot from Topspin 4 showing that the T1/T2 analysis button is accessed via the Applications tab … Dynamics button (which is a different location than that in Topspin 3)

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Enjoy!