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IUPAC Recommendations (iupac + recommendation)

Distribution by Scientific Domains

Chemistry	75%

Selected Abstracts

Further Conventions for NMR Shielding and Chemical Shifts (IUPAC Recommendations 2008),

MAGNETIC RESONANCE IN CHEMISTRY, Issue 6 2008
Applied Chemistry Physical, Biophysical Chemistry Division, International Union of Pure
Abstract IUPAC has published a number of recommendations regarding the reporting of nuclear magnetic resonance (NMR) data, especially chemical shifts. The most recent publication [Pure Appl. Chem.73, 1795 (2001)] recommended that tetramethylsilane (TMS) serve as a universal reference for reporting the shifts of all nuclides, but it deferred recommendations for several aspects of this subject. This document first examines the extent to which the 1H shielding in TMS itself is subject to change by variation in temperature, concentration, and solvent. On the basis of recently published results, it has been established that the shielding of TMS in solution [along with that of sodium-3-(trimethylsilyl)propanesulfonate, DSS, often used as a reference for aqueous solutions] varies only slightly with temperature but is subject to solvent perturbations of a few tenths of a part per million (ppm). Recommendations are given for reporting chemical shifts under most routine experimental conditions and for quantifying effects of temperature and solvent variation, including the use of magnetic susceptibility corrections and of magic-angle spinning (MAS). This document provides the first IUPAC recommendations for referencing and reporting chemical shifts in solids, based on high-resolution MAS studies. Procedures are given for relating 13C NMR chemical shifts in solids to the scales used for high-resolution studies in the liquid phase. The notation and terminology used for describing chemical shift and shielding tensors in solids are reviewed in some detail, and recommendations are given for best practice. © 2008 IUPAC. Reprinted with permission from Pure Appl. Chem. 2008; 80: 59. This article can be freely downloaded from http://www.iupac.org/publications/pac/80/1/0059/ and can be copied, provided acknowledgement to IUPAC is given. [source]

NMR nomenclature: Nuclear spin properties and conventions for chemical shifts (IUPAC recommendations 2001),

CONCEPTS IN MAGNETIC RESONANCE, Issue 5 2002
Robin K. Harris
Abstract A unified scale is recommended for reporting the NMR chemical shifts of all nuclei relative to the 1H resonance of tetramethylsilane. The unified scale is designed to provide a precise ratio, ,, of the resonance frequency of a given nuclide to that of the primary reference, the 1H resonance of tetramethylsilane (TMS) in dilute solution (volume fraction, , < 1%) in chloroform. Referencing procedures are discussed, including matters of practical application of the unified scale. Special attention is paid to recommended reference samples and values of , for secondary references on the unified scale are listed, many of which are the results of new measurements. Some earlier recommendations relating to the reporting of chemical shifts are endorsed. The chemical shift, ,, is redefined to avoid previous ambiguities but to leave practical usage unchanged. Relations between the unified scale and recently published recommendations for referencing in aqueous solutions (for specific use in biochemical work) are discussed, as well as the special effects of working in the solid state with magic-angle spinning. In all, nine new recommendations relating to chemical shifts are made. Standardized nuclear spin data are also presented in tabular form for the stable (and some unstable) isotopes of all elements with non-zero quantum numbers. The information given includes quantum numbers, isotopic abundances, magnetic moments, magnetogyric ratios and receptivities, together with quadrupole moments and linewidth factors (where appropriate). © 2001 IUPAC. Concepts Magn Reson 14:326,346, 2002 [source]

The Current Usage of Selectivity Coefficients for the Characterization of Ion-Selective Electrodes.

ELECTROANALYSIS, Issue 12 2003
A Critical Survey of the 2000/2001 Literature
Abstract The articles describing new ion-selective electrodes published during the years 2000/2001 in eight leading analytical chemistry journals have been surveyed. Compliance with the IUPAC recommendations of the procedures used for characterizing the selectivity of the new electrodes has been checked. It was found that the information accompanying the selectivity data obtained according to the procedures recommended by IUPAC or their variations was frequently insufficient for interpreting of the electrode behavior and comparing with other sets of data, thus reducing the significance of the values provided. Some criteria for improving the communication between researchers in the field are suggested. [source]