An investigation of methods proposed for the analysis of the various forms of fluoride in toothpaste

Analytical methods for the determination of soluble fluoride, soluble fluorine and total fluorine derivatives in toothpaste were investigated. Potentiometric determinations of soluble fluoride in TISAB-toothpaste slurries were shown to be inaccurate. Based on recovery measurements, analyses for soluble fluoride and soluble fluorine derivatives in the supernatant liquid were found to be reliable provided the slurrying time was standardized. A gas chromatography method for the analysis of total fluorine, using the silane derivative fluoride, was compared with methods involving ashing and distillation prior to colorimetric or potentiometric analysis.