Indirect Referencing of31P and19F NMR Spectra

✍ Scribed by Till Maurer; Hans Robert Kalbitzer

• Publisher: Elsevier Science
• Year: 1996
• Tongue: English
• Weight: 53 KB
• Volume: 113
• Category: Article
• ISSN: 1064-1866
• DOI: 10.1006/jmrb.1996.0172

✦ Synopsis

Accurate referencing of NMR spectra is of vital impor-latter compound is again strongly pH dependent. We have estimated the J factors for these substances (Table 1). Since tance for both reproducibility and correlation of chemical and structural properties to the chemical shift. The task is the geometry of the container with the external reference and its orientation to the B 0 field influence the chemical-often not that straightforward. For most of the heteronuclei, no ideal or nearly ideal reference compound exists that ful-shift values measured, we estimated the J factors for two arrangements, a coaxial capillary oriented parallel to the B 0 fills the conditions of good solubility in the solvent used (in biological NMR, usually water), no interaction with the magnetic field and a spherical container positioned in the center of the sensitive volume. In the past, the capillary molecules under investigation, sufficient stability, negligible dependence of the chemical shift on factors such as tempera-system has been used more often but has the severe disadvantage that the reference resonance frequency n R is strongly ture, pH, and ionic strength, and a narrow resonance line at the left or right edge of the spectrum. A possibility for influenced by the difference in the susceptibilties x R and x S of the reference solution R and the sample S (6-9). It has overcoming these problems, at least partly, is the use of