gCOSY

Set up appropriate 1H parameters. Normally should acquire 1D 1H spectrum first.

pw = 1H pulse, should be 90º pulse

tpwr = high power for 1H; should be set according to pw, or is correlated to pw.

nt = number of scans, should be multiple of 2, but 1 is acceptable

ni = number of t1 increments, points in t1 dimension, must be even number, preferably at least 128, 256 is preferable

np = number of points in t2 dimension, must be even number, 2048 is standard

d1= relaxation delay; the default value is 1 second and is normally ok, but aromatic (or vinyl or methyl) protons usually need 1.5-2.5 seconds for optimal signal-to-noise


Steps:

1) Acquire 1 scan of 1H 1D experiment. Set cursors ~0.5 ppm beyond last proton resonance on both sides of spectrum, type command:
movesw

2) Re-acquire 1H 1D experiment (this is only required for 1H 1D on side of 2D spectrum)

3) Move parameters to another experiment. To move parameters from experiment 1 to experiment 3 type command:
mp(1,3)

4) Change to experiment 3, type command:
jexp3

5) Set gCOSY parameters with setup macro, type command:
gCOSY

6) Spin will likely turn off, if it does not, open Acqi window and manually turn it off. Lock Level should not drop more than ~5 %-10 %. If it does, you should reshim non-spin shims- X1, Y1, XZ, and YZ, and on higher field (500/600) X2Y2 and XY

7) Set the number of scans (nt) to appropriate value, generally 1 or 2 (it is preferable for nt to be a multiple of 2; nt might need to be increased for sufficient signal-to-noise, generally nt = 2 is sufficient if decent 1H spectrum
can be acquired in 128 scans), type:
nt=2

8) Set the number of points in t1 dimension (second dimension) (ni), generally 128-256 are suggested (if very high resolution is required to define crosspeaks, set ni to 400 or more), type
ni=256

9) Set d1 time, the default value is 1 second and is normally ok, but aromatic (or vinyl or methyl) protons usually need 1.5-2.5 seconds for optimal signal-to-noise

10) Start acquisition, type command:
go

11) At end of experiment, set appropriate weighting functions and linear prediction parameters, type commands:
setLP1
sqsinebell

12) If fn parameter now equals 4096, processing will be slow, then type:
fn = np
fn1 = fn

13) Process 2D type command:
wft2d

14) Switch f1 and f2 axes (make f2 the x-axis), type
trace = 'f2'

15) Display as contour plot, type command:
dp10

16) If spectrum has streaks running across the page, type command:
foldt

17) Spectrum should be appropriately referenced already, but you should confirm this; if necessary re-reference by putting cursor on appropriate diagonal peak and type (assuming CDCl3):
rl(7.26p)
rl1(7.26p)
dp10

18) Adjust vertical scale with vs +20% and vs -20% menu buttons or with middle mouse button or manually changing the parameter, vs2d, so vs2d = 100 (the lower the number, the less noise displayed), then redraw 2D with dp10 command

19) Print with 1D on side with 1D in experiment 1:
plcosy(10,1.2,1)

20) or Print with full rectangle, type:
full
dp10
p10

21) Save data, type:
svf('filename')