Determination of Fluoride in Water by Reversed-Phase High-Performance Liquid Chromatography using F−-La3+-Alizarin Complexone Ternary Complex

A method for the determination of fluoride by reversed-phase, high-performance liquid chromatography (RP-HPLC) is described. Fluoride, La3+ and alizarin complexone form F-La3+-alizarin complexone ternary complex, which is separated from the matrix on a RP, Ultrasphere C18 column (250 × 4.6 mm, 5 μm) using methanol-water (19:81, v/v) mobile phase at 1.00 mL min−1; detection at 568 nm. The calibration graph was linear from 1.0–150 ng mL−1 for fluoride with a correlation coefficient: 0.9993 (n=6). The detection limit was 0.2 ng mL−1. The method was successfully applied to the determination of fluoride in river and tap water. Recovery was: 94–102%, RSD in the range: 1.9 –3.6%.