4. Acquisition

Time requirement: 25 min Sample: 3% strychnine in CDCl₃3.

Record normal ¹H and 3C NMR spectra of the sample and optimize the spectral widths. Change to the 2D mode of the spectrometer and load the ACCORD-HMBC pulse program. You have to set:

td2: 2 k data points in F» tdl: 256 data points in F; sw2: 10 ppm swl: 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: 180° ¹H transmitter pulse p3–p8: 90° ¹³C decoupler pulse dl:2s 2J min +0. 146J max –J min lated from 'J(C,Hmax) = 163 Hz and 'J(C,Hmin) = 128 Hz and effective gradient duration of 1.05 ms 2J max –9-146J max –J min lated from 'J(C,Hmax) = 163 Hz and 'J(C,Hmin) = 128 Hz and effective gradient duration of 1.05 ms initial value for long-range polarization, 200 ms, calculated from *3.(C,H) = 2.5 Hz; d4 is decremented during the experiment. The decrement is cal- culated from the ACCORDION range (200 ms – 20 ms)/ tdl = 0.7 ms cor- responding 2.5 to 25 Hz.

start increment for ¢, evolution: 3 μs increment for f, evolution: 1/[2-sw1] g1–g8: sinusoidal-shaped field gradients, 1 ms duration and ca. 0.1 T/m strength, ring-down delays (50 μs), lock blanking and gradient coil blanking switches according to actual instrumentation used. Gradient strength ratio: 15 : -10: -5 : 50:30: 40:-5:5 BC decoupler attenuation and 90° pulse for GARP [ca. 70 μs at 12 dB]

5. Processing

Apply zero-filling in F, to 512 words in order to have a matrix of 1kx512 real data points. Before Fourier transformation use an exponential window in F, with lb = 5 Hz