Abstract
To develop a highly sensitive yet easy to use method for determining the fluoride ion in salt, we examined the use of ion chromatography (IC) after the application of zirconium-loaded solid phase extraction (Zr-SPE). In IC, fluoride and iodate ions were separated by a high capacity column with a weak concentration (0.75 mM) of sodium carbonate in the mobile phase. The sodium hydroxide concentration in the IC sample solution was adjusted to 30 mM such that a sufficient number of theoretical plates was obtained. On the other hand, the eluent for Zr-SPE required a 50 mM concentration to elute the fluoride ions from the solid phase. Then, the eluate was diluted to adjust the sodium hydroxide solution to 30 mM. For salt with an aluminum, the recovery of the fluoride ions in Zr-SPE was adversely affected. Thus, the aluminum was removed from the sample solution through the extraction of acetylacetone, which improved the recovery of the fluoride ions. We applied this method to real samples to confirm the efficacy of the method. Using this method, the fluoride ion in salt can be determined easily and very accurately.
