Simultaneous determination of fluoride and monofluorophosphate in toothpastes by supressed ion chromatography

Suppressed ion chromatography with a highly selective and high capacity anion-exchange column is used for the determination of anionic compounds in ten commercially available toothpastes. Minimal sample preparation is needed, requiring only dilution and filtration over a solid-phase extraction cartridge. Quantitative analysis of fluoride and monofluorophosphate, as well as chloride, nitrate, orthophosphate, and sulfate is achieved in one chromatographic run with a total analysis time of 25 minutes. Optimized analytical conditions are validated in terms of accuracy, precision, and total uncertainty, and the results demonstrate the reproducibility of ion chromatography. The coefficient of determination for the anions ranges from 0.9896 to 0.9997. The spiked recoveries for the anions are 88–108%. The change in the fluoride content of the toothpaste with storage time is investigated.