Strange phenomena when I'm doing TOCSY in D2O/H2O (10%) with water suppression by excitation sculpting employing the mlevesgpph pulse sequence from the Bruker pulse library. Water suppression is working quite nice, but:
The spectrum seems not to be symmetically as I'm used to when I record Homo 2D NMR spectra (COSY, NOESY, TOCSY) in organic solvents without water suppression. The signals in the region above the diagonal are much more intense than that in the lower sector below the diagonal.
I've tried already diffferent processing methods but nothing really helps. What may be the reason for this phenomena?
Thanks in advance,
Lars
The excitation sculpting might attenuate your signals. This suppression method can attenuate signals up to 1 - 1.5 ppm away from the water. The suppression affects the acquisition of F2 dimension. In F1 there is no suppression.
You can choose longer selective pulses in the "es" part. for example double p12 and lower the power by 6 dB.
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