Direct Determination of Sodium Fluoride and Sodium Monofluorophosphate in Toothpaste by Quantitative ¹⁹F-NMR: A Green Analytical Method

ABSTRACT

Sodium fluoride and sodium monofluorophosphate are often used as fluoridizers in oral care products to prevent dental caries. By quantitative ¹⁹F-NMR, their contents in toothpaste were simultaneously determined. This is a simple, fast, interference-free, and green analytical method for the determination of sodium fluoride and sodium monofluorophosphate in toothpaste.

KEYWORDS:

• quantitative ¹⁹F-NMR
• sodium fluoride
• sodium monofluorophosphate
• toothpaste

ACKNOWLEDGMENTS

We thank Dr. Lu Shan (Bruker Biospin AG Beijing Representative Office) for useful discussion, and acknowledge the financial support from the Ministry of Education of China for the research on green analytical chemistry (NCET-04-0869) and also from the Scientific Foundation for the Returned Overseas Chinese Scholars, State Education Ministry (2008890–19–3).

Notes

^a Number of measurements: 5; M: mass in milligram; M′: the average mass found by ¹⁹F-NMR; I: the average integral area of peak; x and s: analyte (NaF) and internal standard (CF₃COONa); Er: relative error; RSD: relative standard deviation.

^a Number of measurements: 5;

^b Average value ± standard deviation;

^a Number of measurements: 5.

^b mass of fluoride (NaF or Na₂PO₃ · F) by qNMR determination.

^c mass of fluoride (NaF or Na₂PO₃ · F) by qNMR determination after adding standard material.

^a average value ± standard deviation of 5 measurements.

An invited paper submitted to a special issue on Green Spectroscopy and Analytical Techniques, organized by Professor Miguel de la Guardia, of the Department of Chemistry, University of Valencia, Spain, and Professor Arabinda Kumar Das, of the Department of Chemistry, University of Burdwan, West Bengal, India.