Sodium trimethylsilylpropanesulfonate (DSS) is the organosilicon compound with the formula (CH3)3SiCH2CH2CH2SO3−Na+. It is the sodium salt of trimethylsilylpropanesulfonic acid. A white, water-soluble solid, it is used as a chemical shift standard for proton NMR spectroscopy of aqueous solutions.[1] The chemical shift, specifically the signal for the trimethylsilyl group, is relatively insensitive to pH.[2]
The proton spectrum of DSS also exhibits resonances at 2.91 ppm (m), 1.75 ppm (m), and 0.63 ppm (m) at an intensity of 22% of the reference resonance at 0 ppm.
Alternatives
Sodium trimethylsilyl propionate (TSP) is a related compound used as an NMR standard. It uses a carboxylic acid instead of the sulfonic acid found in DSS to confer water solubility. As a weak acid, TSP is more sensitive to changes in pH.
4,4-Dimethyl-4-silapentane-1-ammonium trifluoroacetate (DSA) has also been proposed as an alternative, to overcome certain drawbacks of DSS.[3]
^Nowick, James S.; Khakshoor, Omid; Hashemzadeh, Mehrnoosh; Brower, Justin O. (2003). "DSA: A New Internal Standard for NMR Studies in Aqueous Solution". Org. Lett.5 (19): 3511–3513. doi:10.1021/ol035347w. PMID12967312.