How to measure H1 T2 in organic solvents:

1. Don’t spin the sample, do topshim with X-Y… items instead. Run 1D PROTON first, and find proper o1, sw, and p1 by pulsecal.
2. Load H1_CPMG_T2_hw ( using cpmg sequence) from …/par/user parameter folder, besides using most of the default parameters, update p1, o1, sw.
3. (For the std CDCl3 sample in B500-Chewie) Try to use d1=20s (to 150s); d20=10ms (2*d20 = the fixed delay time between two 180° proton pluses in CPMG train; d20 should be << 1/J; but > 50*p2); ns=8 or 16.
4. Edit vclist, and choose ncyc as even numbers, like 2, 20, 50, 100, 300, 400, 500, 700, 1000; and then set TD1 as the total number of ncycs in vclist (9 here).
5. rga, expt (using expt to show the total nmr time will be shorter than the real total time), and zg.

Note:

1. T2 delay time = ncyc*(2*d20 + p2); here p2 is 180° H1 pulse length.
2. So the ncyc in vclist is corresponding to the T2 delay time as: 0.040052s, … 20.026s, (d20=10ms, p2=26us on B500-Chewie here).

Process with T1T2 Application:

• Do the calculations with Excel or manually and convert vclist’s ncyc into T2 delay time points with the above formula and save as “vdlist” filename inside the original data folder.
• Next, process T2 data just like T1’s. Be careful that:
• edp or select ProcPars, set SI for F1 to 9, but return to 16, since SI only choose next highest power of 2 for F1.
• Set SPECTYP to PSEUDO2D.
• xf2↙, .ph, select Rows button to do phase correction, save & exit, abs2↙,
• Applications → Dynamics → T1T2 → FID →Spectrum → 1
• Peaks/Ranges → Manual integration → define Ranges → integrate regions (choose more peaks…) → Export regions to Relaxation module and .ret.
• Go to Relaxation tab → check parameters (make sure to choose: uxnmrt2 as Function Type; vdlist as List Name; use intensity to fit, etc.) → press “>” to fitting, click full spectrum button, click lin; and then press “>>>” to fit all other peaks, then click “show report”, save into a text file in the original data folder.

Hongwei edited on 5/12/2023