Tetramethylsilane
[2] Tetramethylsilane is the accepted internal standard for calibrating chemical shift for 1H, 13C and 29Si NMR spectroscopy in organic solvents (where TMS is soluble).Because of its high volatility, TMS can easily be evaporated, which is convenient for recovery of samples analyzed by NMR spectroscopy.[3] Because all twelve hydrogen atoms in a tetramethylsilane molecule are equivalent, its 1H NMR spectrum consists of a singlet.The majority of compounds studied by 1H NMR spectroscopy absorb downfield of the TMS signal, thus there is usually no interference between the standard and the sample.[4] In a fully decoupled 13C NMR spectrum, the carbon in the tetramethylsilane appears as a singlet, allowing for easy identification.