Solvent suppression method for LC-NMR and high-resolution-NMR
AssigneeVarian Associates, Inc.
InventorsStephen H. Smallcombe, Steven L. Patt, Paul A. Keifer
Life of this patent
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Abstract
Improved solvent suppression in NMR data is achieved using pulse sequences wherein each of a series of selective excitation pulses are followed by a magnetic gradient pulse and a delay, where the magnetic gradient pulse amplitudes monotonically decrease by a selected fraction of the preceeding gradient pulse. Decoupling a second nucleus during selective excitation pulses has been shown to be efficacious for suppression of organic solvents.
Claims12
A pulse sequence for excitation of magnetic resonance phenomena in liquid samples comprising I and S nuclei, while suppressing solvent magnetic resonance phenomena therein, comprising
- a) selectively irradiating I nuclei of said sample with a plurality of spaced selective RF pulses to excite magnetic resonance thereof,
- b) selectively irradiating S nuclei of said sample with a plurality of spaced selective RF pulses concurrently with step a), to excite magnetic resonance thereof,
- c) applying to said sample a plurality of magnetic field gradient pulses, each said gradient pulse following corresponding irradiation pulses of S and I nuclei, each said gradient pulse having a duration less than the interval between consecutive I and S irradiation pulses, the first gradient pulse having a selected amplitude and each successive gradient pulse having an amplitude of a selected fraction of the preceding gradient pulse,
- d) applying a read pulse to said I spin system and acquiring the time domain waveform of the de-excitation of said I spin system.
A pulse sequence for excitation of magnetic resonance phenomena in liquid samples comprising selected nuclei, while suppressing solvent magnetic resonance phenomena therein, comprising
- a) selectively irradiating said selected nuclei of said sample with a plurality of spaced selective RF pulses to excite magnetic resonance thereof,
- b) applying to said sample a plurality of magnetic field gradient pulses, each said gradient pulse following corresponding irradiation pulses of said selected nuclei, each said gradient pulse having a duration less than the interval between consecutive irradiation pulses, the first gradient pulse having a selected amplitude and each successive gradient pulse having a monotonically decreasing amplitude of a selected fraction of the preceding gradient pulse,
- c) applying a read pulse to the spin system of said selected nuclei and acquiring the time domain waveform of the de-excitation of said spin system.
A method for supression of magnetic resonance phenomena for selected spectral components resulting from NMR excitation of a liquid sample comprising heteronuclear molecules comprising first nuclear species and second nuclear species coupled thereto, said method comprising the steps of,
- a) exciting to saturation said first nuclear species by appplying to said sample a plurality of selective RF pulses spaced in time and applying a like plurality of magnetic gradient pulses, each of said magnetic gradient pulses offset in time alignment with a corresponding one of said plurality of RF selective pulses,
- b) concurrently with step a), applying decoupling radiation to said second nuclear species and,
- c) applying a read pulse to said first nuclear species and acquiring a waveform representative of the de-excitation thereof.
Dependencies are inferred from the claim text.