2D Double Quantum & Multiple Quantum COSY Experiments

 

The two-dimensional Double Quantum Filtered COSY experiment correlates protons.  The DQ Filter reduces the diagonal. Before setting up the DQCOSY experiment, see Acquiring and Processing 2D Experiments. See the Varian Guide to NMR Experiments for a complete description of this experiment.

Variations of the DQCOSY experiment

Higher orders of quanta may be used to filter the COSY experiment. Type mqcosy and change the following parameters from the standard DQCOSY parameters:

·        qlvl = level of quantum filtration

·        nt = multiple of 2*qlvl

Acquiring the experiment:

1.      Join the experiment in which the 1H reference spectrum was collected. Type dqcosy.

2.      Type dg. Adjust the parameters listed below for the standard DQCOSY:

·        sfrq=set by spectrometer

·        dm=’n’

·        tn=’H1’

·        sw1 = sw from 1H reference spectrum

·        at = set by spectrometer

·        ni = multiple of 64

·        np=2048

·        phase=1,2

·        sw = sw from 1H reference spectrum

·        dp=’n’

·        ss=2

·        hs=’n’

·        tpwr = listed at console

·        sspul=’n’

·        pw = 1H 90° pulse width

·        p1=0

·        d1 = 1H relaxation delay (1-2 * 1H T1)

·        d2=0

·        rf1 = rf from 1H reference spectrum

·        presat=0

·        rfp1 = rfp from 1H reference spectrum

·        tof = tof from 1H reference spectrum

·        wp1 = wp from 1H reference spectrum

·        nt = multiple of 4

·        sp1 = sp from 1H reference spectrum

·

3.      Change ni, nt, and d1 to suit your scheduled time.

 

 

 

 

 

The vertical  (non-acquisition) resolution equals sw1/2ni.

 

Typical values are listed below for sw1=4400

d1

ni

nt

Time

Vertical resolution

1.5

128

4

0:15

17.2 Hz

1.5

256

4

0:31

8.6 Hz

1.5

512

4

1:02

4.3 Hz

1.5

128

16

1:01

17.2 Hz

1.5

256

16

2:03

8.6 Hz

1.5

512

16

4:09

4.3 Hz

1.5

128

64

4:03

17.2 Hz

1.5

256

64

8:10

8.6 Hz

1.5

512

64

16:37

4.3 Hz

2.25

128

4

0:21

17.2 Hz

2.25

256

4

0:43

8.6 Hz

2.25

512

4

1:28

4.3 Hz

 

 

*** TURN OFF THE SPINNER***

 

Type au to start the acquisition.

 

Processing, Displaying, and Plotting:

Process using the procedure for Processing a 2D Phase-Sensitive Experiment. Plot All Contours. The DQCOSY spectrum may be symmeterized by typing foldt.