Easy implementation on AVANCE spectrometers.

The most important parameter to optimize is the mixing time (d8).

The standard way to implement a NOESY block with water flip-back is:

... "DELTA=d8-p16-d16-p11-d12-54u" ... p1 ph1 DELTA 50u UNBLKGRAD p16:gp1 d16 pl0:f1 (p11:sp1 ph2:r):f1 4u d12 pl1:f1 p1 ph3 ...

in which:

• p1 is the 90 1H pulse (in usec) applied at high power level pl1 from the f1 channel.
• d8 is the mixing NOESY time (in seconds). The delay DELTA is automatically calculated from the expression "DELTA=d8-p16-d16-p11-d12-54u"
• gpz1=50 stands for a purgued gradient of duration p16 (about 1ms)
• Parameters for the water-selective 90 pulse: p11 is the duration, sp1 is the power level, spnam1 is the shape, and phcor2 is the phase difference between hard and soft pulses.
• All phases may be specified at the end of pulse program.