BRAINCAKEThe TMS Standard
Chemical shifts are measured relative to a reference compound, tetramethylsilane (TMS), Si(CH3)4. A small amount of TMS is added to the sample, and its peak is defined as δ = 0 ppm. Every other peak is measured from it.
Si(CH3)4: four CH3 groups bonded to a central silicon atom
TMS is used as the standard because:
• All 12 of its H atoms are in the same environment, and all 4 of its C atoms are in the same environment, so it gives a single, strong peak in both 1H and 13C NMR.
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More in NMR Spectroscopy
- Nuclear Magnetic Resonance
- Chemical Shift
- Deuterated Solvents
- 13C NMR Spectroscopy
- Interpreting 13C NMR Spectra
- 1H NMR Spectroscopy
- Integration Traces
- Spin-Spin Splitting
All 11 lessons in NMR Spectroscopy · All AQA A-level Chemistry topics