Comparing Parameter Settings in Cyclenoe

Cyclenoe is one of the trickiest 1D experiments to set up in order to get a clean spectrum. Besides spectrometer and probe stability, the recycle delay (d1) and saturation time (sattime) settings, among others, may have a big impact on how clean the difference spectrum is. The following compares results from several cyclenoe experiments on the same compound collected with different d1 and sattime values within a 2 hour span. The experiments took from 10 to 25 mins each. Except for the d1 and sattime differences, all other parameters are kept the same:

• Temperature is regulated at: 22C
• Spin is turned OFF
• intsub='y' (internal subtraction of on- and off-resonance saturation spectra)
• satfrq (on-resonance selective saturation) is set to peak at 5.90ppm
• control (off-resonance selective saturation position) is set to ~ 5.00ppm
• cycle='y' (uses frequency cycling during saturation)
• spacing=13.5 (spacing between multiplet, measured)
• pattern=3 (multiplet pattern is set to 3 for triplet)
• tau=0.1 (period spent on single irradiation during frequency cycling, 0.1 is default)
• satpwr= -16 (minimal power)
• mix=0 (mixing time, not used)
• sspul='y' (trim pulses before d1), default
• nt=32 (multiple of 32 if intsub='y')

Longest T1 of the Strychnine sample is measured

T1_max ~ 2.9 sec. See the cyclenoe setup page for details of the T1 measurement.

NOE difference spectra from cyclenoe

The experiment done with d1=16 (~5*T1_max) sattime=8 (~3*T1_max) gives the cleanest spectrum for this sample, excluding other unknown factors.

1H spectrum
d1=8 sattime=8
d1=8 sattime=4
d1=2 sattime=8
d1=16 sattime=8
d1=8 sattime=16

H. Zhou updated Oct 2010