TROSY is usually applied to large 15N-labeled biomolecules in high magnetic fields. Easy implementation on AVANCE spectrometers equipped with pulsed field gradients.

The standard way to implement the TROSY block is:

... (p1 ph8) p16:gp2 d16 DELTA2 (CEN_HN2 p2 ph1) (p22 ph1):f3 DELTA2 p16:gp2 d16 (CEN_HN1 p1 ph1) (p21 ph8):f3 p16:gp3 d16 DELTA1 pl0:f1 (p11:sp1 ph3:r):f1 4u 4u pl1:f1 (CEN_HN2 p2 ph1) (p22 ph1):f3 4u pl0:f1 (p11:sp1 ph3:r):f1 DELTA1 p16:gp3 d16 pl1:f1 4u BLKGRAD (p21 ph1):f3 ...

in which:

• p1 and p2 are the 90 and 180 1H pulse (in usec), respectively, applied at high power level pl1 from the f1 channel.
• p21 and p22 are the 90 and 180 15N pulse (in usec), respectively, applied at high power level pl3 from the f3 channel.
• The delays CEN_HN1=(p21-p1)/2 and CEN_HN2=(p22-p2)/2 are automatically calculated.
• The delays DELTA1=d26-p11-p16-d16-8u and DELTA2=d26-p16-d16 are also automatically calculated from the d26=1/(4*J_NH) value.
• Parameters for the water-selective 90 pulse: p11 is the duration, sp1 is the power level, spnam1 is the shape, and phcor3 is the phase difference between hard and soft pulses.
• The gradient are used to minimize imperfect 180 pulses and for WATERGATE water suppression: gpz1=18 and gpz2=44.
• All phases may be specified at the end of pulse program.