p1:	x	p2:	(x)₂, (−x)₂	p3:	x, −x	p4:	(x)₄, (−x)₄
p5:	y	p7:	x
aq:	(x, −x)₂, (−x, x)₂
p6:	spin-lock of composite 180° pulses (90°, 180°, 90°) using the MLEV-17 sequence:

[90(ph1), 180(ph2), 90(ph1)]₂	ph1: x, ph2: y
[90(ph3), 180(ph4), 90(ph3)]₃	ph3: −x, ph4: −y
[90(ph1), 180(ph2), 90(ph1)]₂
[90(ph3), 180(ph4), 90(ph3)]₃
[90(ph1), 180(ph2), 90(ph1)]₃
[90(ph3), 180(ph4), 90(ph3)]₂
[90(ph1), 180(ph2), 90(ph1)]₁
[60(ph2)]

4. Acquisition

Time requirement: 1.2 h

Sample: 3% strychnine in CDCl₃.

Record normal ¹H and ¹³C NMR spectra of the sample and optimize the spectral widths for CH_n signals. Change to the 2D mode of the spectrometer and load the gs-HMQC-TOCSY pulse program. You have to set:

td2	1 k data points in F₂
td1	256 data points in F₁
sw2	10 ppm
sw1	165 ppm
offset of ¹H frequency	middle of ¹H NMR spectrum
offset of ¹³C frequency	middle of ¹³C NMR spectrum
p1	90° ¹H transmitter pulse
p2, p7	180° ¹H transmitter pulse
p3, p4	90° ¹³C decoupler pulse
p5	2.5 ms ¹H trim pulse
p6	series of composite 180° pulses (90°, 180°, 90°) at transmitter attenuation of spin-lock; 90° pulse-width and transmitter attenuation typically in the order of 40 μs and 16 dB, corresponding to an effective spin-lock field of ca. 7000 Hz (magnetic-field-dependent). Last pulse 60° according to MLEV-17 scheme. Duration of spin-lock set to 81.8 ms by loop parameter of spin-lock sequence. The loop parameter must be an even number (30 was used here).
d1	2 s
d2	1/[2J(C,H)] = 3.57 ms, calculated from ¹J(C,H) ≈ 140 Hz
d3	d2 minus duration of gradient pulse
d4	equal to duration of gradient pulse
start increment for t₁ evolution	3 μs
increment for t₁ evolution	1/[2·sw1]