Document Detail

Rapid parameter optimization of low signal-to-noise samples in NMR spectroscopy using rapid CPMG pulsing during acquisition: application to recycle delays.
MedLine Citation:
PMID:  23322645     Owner:  NLM     Status:  Publisher    
A method is presented that combines Carr-Purcell-Meiboom-Gill (CPMG) during acquisition with either selective or nonselective excitation to produce a considerable intensity enhancement and a simultaneous loss in chemical shift information. A range of parameters can theoretically be optimized very rapidly on the basis of the signal from the entire sample (hard excitation) or spectral subregion (soft excitation) and should prove useful for biological, environmental, and polymer samples that often exhibit highly dispersed and broad spectral profiles. To demonstrate the concept, we focus on the application of our method to T(1) determination, specifically for the slowest relaxing components in a sample, which ultimately determines the optimal recycle delay in quantitative NMR. The traditional inversion recovery (IR) pulse program is combined with a CPMG sequence during acquisition. The slowest relaxing components are selected with a shaped pulse, and then, low-power CPMG echoes are applied during acquisition with intervals shorter than chemical shift evolution (RCPMG) thus producing a single peak with an SNR commensurate with the sum of the signal integrals in the selected region. A traditional (13) C IR experiment is compared with the selective (13) C IR-RCPMG sequence and yields the same T(1) values for samples of lysozyme and riverine dissolved organic matter within error. For lysozyme, the RCPMG approach is ~70 times faster, and in the case of dissolved organic matter is over 600 times faster. This approach can be adapted for the optimization of a host of parameters where chemical shift information is not necessary, such as cross-polarization/mixing times and pulse lengths. Copyright © 2013 John Wiley & Sons, Ltd.
Hashim Farooq; Denis Courtier-Murias; Ronald Soong; Hussain Masoom; Werner Maas; Michael Fey; Rajeev Kumar; Martine Monette; Henry Stronks; Myrna J Simpson; André J Simpson
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2013-1-16
Journal Detail:
Title:  Magnetic resonance in chemistry : MRC     Volume:  -     ISSN:  1097-458X     ISO Abbreviation:  Magn Reson Chem     Publication Date:  2013 Jan 
Date Detail:
Created Date:  2013-1-16     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9882600     Medline TA:  Magn Reson Chem     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Copyright Information:
Copyright © 2013 John Wiley & Sons, Ltd.
Department of Chemistry, University of Toronto, 1265 Military Trail, Toronto, ON, Canada, M1C 1A4.
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