Rapid-Pulsing Artifact-Free Double-Quantum-Filtered Homonuclear Spectroscopy: The 2D-INADEQUATE Experiment Revisited
✍ Scribed by Maryse Bourdonneau; Bernard Ancian
- Publisher
- Elsevier Science
- Year
- 1998
- Tongue
- English
- Weight
- 402 KB
- Volume
- 132
- Category
- Article
- ISSN
- 1090-7807
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✦ Synopsis
Rapid pulsing artifacts are observed in the conventional phasemultiple-quantum coherence. Inherent to this class of speccycled carbon-13 2D INADEQUATE experiment. By using the troscopic techniques is the generation of spectral artifacts product operator formalism, it is shown that they result from the resulting from unwanted coherences which reach the reeffects of imperfect 90Њ and 180Њ excitation pulses on the most ceiver despite suitable phase cycling, multiple quantum filabundant molecules containing only one isolated carbon-13 nuters, or tailored pulsed field gradients (3). cleus. The labeled longitudinal magnetization remaining at the Moreover, these experiments suffer considerably from low end of one scan is recycled by the subsequent acquisition, giving sensitivity, particularly for the 2D-INADEQUATE where rise to multiple-quantum (p Å 0, {1, {2, . . .) artifacts in the F 1 only 1 molecule in roughly 8100 gives the AX (or AB) dimension. By considering pairs of scans instead of single scans, system needed for the required double quantum coherence a new phase cycle is proposed. It is based on a scheme for compencompared to the 180 times more intense undesirable single sating for imperfections in the excitation cluster by a proper combination of the pulse phases in two consecutive scans. Because the quantum responses. Of course, this problem is less severe artifacts are 90Њ out of phase compared to the desired signal, a in DQF-COSY, where the loss in sensitivity is only by concomitant rearrangement of the receiver phase achieves supa factor of 2 compared to the standard unfiltered COSY pression of all unwanted signals. Experiments are presented on experiment. It is also less crucial in 2D double-quantum menthol dissolved in CDCl 3 as a test compound. Improvements proton experiments, which have been shown to be more in spectrum quality as well as increased sensitivity are discussed. sensitive and more suitable than DQF-COSY for a complete ᭧ 1998 Academic Press
analysis of the protein fingerprint region with water saturation 2 (4, 5). As a result, there is a constant temptation to speed up data collection by allowing only partial relaxation,