A Study on the Appropriate Time to Keep Fluoride Standard Solution

Abstract

          Objective: To study the appropriate storage duration of the standard fluoride solutions and to test the level of fluoride ions using calibration curve obtained by Selective Electrode method.

          Materials and methods: The study samples comprised of standard fluoride solutions with fluoride concentrations of  0.1, 1.0 and 10.0 ppm The solutions were stored at 4^oC for a total of 9 weeks and the average fluoride content of each solution was checked on a weekly basis using Selective Electrode method.  Freshly prepared fluoride solution was used to make control calibration curves and compared with the stored samples at different durations. Data analysis was done using SPSS version 16.

          Results: In this study the fluoride concentration of 0.1, 1.0, and 10 ppm was stored at an extreme temperature of 4C for a total of 9 weeks. There was no change in the fluoride concentration (Mean ± SD) from week 1 to week 4. However, in 10.0 ppm fluoride solution there were noticeable changes at week 5 (10.94±0.055) and week 9 (10.78±0.045).

          Discussion and Conclusion: The 0.1, 1.0, and 10 ppm fluoride solutions could be stored for up to 4 weeks at 4C without significant changes in their average concentration. During long storage periods, a calibration curve should be created to test the concentrations of stored fluoride solutions.