NMR of Toothpaste

Some common household products contain many NMR active nuclides able to provide information on the identify the major components of the product.  Toothpaste is such an example.  It contains abrasives, surfactants, cleansers, fluoride, sweeteners, foaming agents, flavors, etc.... A survey of some of the NMR active nuclides can reveal the major components.  The figure below shows the ¹⁹F, ³¹P,  ²³Na, ¹³C and ¹H NMR spectra of a D₂O slurry of Crest Complete toothpaste acquired on a 300 MHz spectrometer as well as the ²⁹Si CP/MAS NMR spectrum of a sample of dried Crest Complete toothpaste, collected on a 200 MHz spectrometer.  Except for the ²⁹Si CP/MAS spectrum, which was collected over several hours, all other spectra were collected in a matter of minutes.

The ¹⁹F spectrum is consistent with the fluoride ion which is a well known agent for preventing tooth decay.  The ³¹P spectrum collected with ¹H decoupling shows two major peaks consistent with diphosphate and phosphate anions.  Salts of these anions are used as water retention agents, stabilizers and emulsifiers.  The ²³Na spectrum shows a single peak consistent with sodium cations, balancing the charge for the fluoride, diphosphate and phosphate anions.  The ¹³C and ¹H NMR spectra show one major component consistent with sorbitol, commonly used as a sweetener.  Other minor components are evident in both the aliphatic and aromatic regions of the ¹H and ¹³C spectra.  The ²⁹Si CP/MAS spectrum of the dried toothpaste is consistent with silica, which is used as an abrasive.  The two peaks are due to Q4 (Si(OSi)₄) and Q3 (Si(OH)(0Si)₃) silicon sites.  It should be noted that there are many other components including flavoring agents, coloring agents and preservatives present in concentrations which would require much more time and attention to identify.