a sensitivity-enhanced 3D HCCH-COSY experiment with (the pulse program hcchdigp3d

Channel	f1	f2	f3
Nucleus	1H	13C	15N
Offset	o1p	o2p	o3p
Value	4.75 ppm	38 ppm	115.5 ppm

 

The following hard and shaped pulses applied on the three channels must be previously calibrated:

• Hard 90º and 180º ¹H pulses via the observe f1 channel (p1 and p2 at pl1).
• Hard 90º and 180º ¹³C pulses via the decoupler f2 channel (p3 and p4 at pl2).
• Low power 90º ¹³C pulse for ¹³C-¹³C TOCSY transfer (using DIPSI-3) via the decoupler f2 channel. (p9 (about 25u) at pl15).
• Selective 180º ¹³C pulse applied off resonance on the CO resonances via the decoupler f2 channel (p14 (about 256u) at sp5, using spnam5=G3.256, spoff5=135).
• 90º ¹³C pulse for GARP ¹³C decoupling during ¹H acquisition via the decoupler f2 channel (pcpd2 at pl12 using cpdprg2=garp).
• Hard 180º ¹⁵N pulse via the decoupler f3 channel (p22 at pl3).

Otherwhise, all required acquisition parameters can be displayed with the ased command. By default:
 

 

Dimension	F3	F2	F1
Nucleus	1H	13C	1H
TD	2048	64	128
Spectral width	CH (14 ppm)	13Caliphatic (75 ppm)	CH  (14 ppm)

 

Interpulse delays:

            d4 is optimized to 1/(4*J_C-H) (1.6 ms)
            d21 is optimized to 1/(6*J_C-H) (1.1 ms)

All other delays are automatically calculated from these values. Gradient parameters are already defined and the user must be set the number of scans and dummy scans (ns=4 and ds=128) as a function of sample concentration. The standard gradient parameters are:

Gradient Number	Strength	Duration	Shape
1	gpz1=16	p16=500u	gpnam1=sine.100
2	gpz2=16	p19=2m	gpnam2=sine.50
3	gpz3=30	p29=300u	gpnam1=sine.100
4	gpz4=60	p30=5m p31=4.4m	gpnam4=sine.100

The ¹³C-¹³C TOCSY mixing time is optimized as a function of the l1 loop using the equation

((p9*54.33*4) * l1) + (p20)

where p9 is the low-power 90 ¹³C pulse of the DIPSI-2 sequence and p20 stands for a 2 ms ¹³C trim pulse, all applied at pl15. Assuming a 13C-mixing pulse of 25us, the l1-value of 1 gives a mixing time of 5.4ms (resulting in transfer over one bond), 2 gives 10.9 ms (transfer up to two bonds), 3 gives 16.3 ms (transfer up to three or more bonds).

The standard processing parameters are set to:
 

Dimension	F3	F2	F1
SI	2048	256	512
MC2	-	States-TPPI	States-TPPI
WDW	QSINE	QSINE	QSINE
Offset	2	2	2
ME_mod	no	LPfc	no
NCOEF	0	32	0

 

List of Related Experiments:

Double-Resonance ¹H-¹³C experiments
Double-Resonance ¹H-¹⁵N experiments
Triple-Resonance ¹H-¹³C-¹⁵N backbone experiments
Triple-Resonance ¹H-¹³C-¹⁵N sidechain experiments