Edward Walker, PhD

qNMR Determination of Fluorine in Toothpastes

Title

qNMR Determination of Fluorine in Toothpastes

Presented By

Edward Walker, PhD 

Weber State University 

Presentation Time

9:45-10:00AM

Abstract

Nuclear magnetic resonance (NMR) has traditionally been used in qualitative analyses, determining structures of organic molecules that contain primarily hydrogen and carbon atoms. The use of NMR for quantitative analyses (qNMR) is rapidly expanding and includes many other elements including fluorine. Toothpastes containing fluoride to help prevent cavities are regulated as “Over-the-Counter” drug products. In the USA, sodium fluoride (NaF) and stannous fluoride (SnF2) are popular fluoride actives. In Europe and other countries, sodium monofluorophosphate (MFP) is more frequently utilized as the active ingredient in toothpastes. Fluoride has traditionally been analyzed by diluting the toothpaste in deionized water and then testing with a fluoride specific ion electrode (SIE). This works well for ionic fluorides as in NaF and SnF2. However fluorine in MFP is covalently bound and does readily not form fluoride ions, thus rendering the SIE useless. We have applied NMR to quantitatively determine the fluorine content in toothpastes for both NaF and MFP active ingredients simultaneously. Furthermore, whole toothpaste is analyzed directly, avoiding any sample preparation.

Meet the Speaker

I am a professor of chemistry at Weber State University and a long time member of the IMWSCC. I earned my PhD in chemistry from Texas Tech University and was a post-doctoral scholar in Biochemical Pharmacology at Stanford University. I have been a professor at WSU for 43 years, where I enjoy teaching and conducting research with my students. I like introducing my students to the chemistry-based industries in our intermountain area. Most of my publications over the years have focused on developing and validating unique analytical methods. One such method, direct analysis of dimethicone in aqueous emulsions by FTIR, was published in the SCC Journal of Cosmetic Science 70(4) 209-216 (2019). Recently, my students and I have been discovering new ways to teach old instruments new tricks, such as measuring fluoride in whole toothpastes.