Merck

Variations on the chemical shift of TMS.

Journal of magnetic resonance (San Diego, Calif. : 1997) (2003-08-14)
Roy E Hoffman
ABSTRACT

The chemical shift of TMS is commonly assumed to be zero. However, it varies by over 1 ppm for 1H and 4 ppm for 13C and shows a correlation with the physical properties of the solvent. Using the commonly accepted convention that TMS always resonates at zero leads to significant errors when comparing chemical shifts in different solvents. A new method for measuring absolute chemical shift with a conventional NMR spectrometer is demonstrated. The observed chemical shift is corrected by measuring and correcting for susceptibility and shape factor. Practical suggestions are made for modifying the current chemical shift standard while maintaining compatibility with earlier literature.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Tetramethylsilane, ACS reagent, NMR grade, ≥99.9%
Sigma-Aldrich
Tetramethylsilane, electronic grade, ≥99.99% trace metals basis
Sigma-Aldrich
Tetramethylsilane, ≥99.0% (GC)
Supelco
Tetramethylsilane, analytical standard, for NMR spectroscopy, ACS reagent