Linked Life Data

19179097

Source:http://linkedlifedata.com/resource/pubmed/id/19179097

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2
pubmed:dateCreated
2009-3-20
pubmed:abstractText
Collecting a truly quantitative carbon-13 spectrum is a time-consuming chore. Very long relaxation delays, required between transients to allow the z-magnetization, M(z), of the spin with the longest T(1) to return to the equilibrium value, M(0), must precede each transient. These long delays also reduce sensitivity, as fewer transients per unit time can be acquired. In addition, sometimes T(1) is not known to within even a factor of two: a conservative guess for the relaxation delay then leads to very low sensitivity. We demonstrate a fresh method to bypass these problems and collect quantitative carbon-13 spectra by swapping the sample volume after each acquisition with a different portion where the magnetization is already equilibrated to M(0). Loading larger sample volumes of 10-20 mL into an unusually long (1520 mm) 5 mm OD. NMR tube and vertically sliding the tube between acquisitions accomplishes the swap. The relaxation delay can then be skipped altogether. The spectra are thus both quantitative, and far more sensitive. We demonstrate the moving tube technique on two small molecules (thymol and butylhydroxytoluene) and show good carbon-13 quantification. The gain in sensitivity can be as much as 10-fold for slowly-relaxing (13)C resonances. These experiments show that quantitative, sensitive carbon-13 spectra are possible whenever sufficient sample volumes are available. The method is applicable to any slow-relaxing nuclear spin species, such as (29)Si, (15)N and other low-gamma nuclei.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Apr
pubmed:issn
1096-0856
pubmed:author
pubmed:issnType
Electronic
pubmed:volume
197
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
237-41
pubmed:dateRevised
2009-11-4
pubmed:meshHeading
pubmed:year
2009
pubmed:articleTitle
Sensitive, quantitative carbon-13 NMR spectra by mechanical sample translation.
pubmed:affiliation
Chemistry Department, University of California, Irvine, CA 92697-2025, USA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, Non-P.H.S., Research Support, Non-U.S. Gov't, Research Support, N.I.H., Extramural