A simplified protocol to determine total fluoride concentration in NaF/ silica-based toothpastes

Aim: To determine total fluoride (TF) concentration in Na2FPO3/Ca-based toothpastes, using fluoride ion selective electrode (F-ISE) by the direct technique, it is necessary to use acid (Ac+) to hydrolyze the FPO3 2- ion and to dissolve insoluble fluoride salts bound to the abrasive. For NaF/silicabased toothpastes, the use of acid is not necessary (Ac-) and a simplified protocol could be followed. Methods: Thus, we evaluated TF concentration in seven brands of NaF/silicabased toothpastes, following the validated conventional Cury’s protocol (Ac+) or a simplification of this protocol (Ac-). Fluoride was analyzed with ISE calibrated with fluoride standard solutions prepared in the same conditions as the samples (Ac+ or Ac-). Results: The mean (±SD; n=21) of TF concentrations (μg F/g) found by Ac+ (971.3±191.2) and Ac- (982.4±201.3) protocols were not statistically different (t test, p=0.22). The TF concentrations found agree with those declared by the manufacturers, except for one toothpaste imported from China. Conclusion: The findings suggest that the determination of fluoride in NaF/silica-based toothpastes can be accurately made using a simplified protocol of analysis.