Spectrophotometric Determination of Fluoride in Groundwater Using Complexes of Flavonoid Chrysin

Abstract

A simple spectrophotometric method is developed for determination of fluoride in drinking water by using complexes of chrysin. The method is based on the reaction of the coloured complexes with fluoride where its colour changes, due to the formation of the colourless fluoride complex and liberating of the free ligand, is dependent on the concentration of fluoride in water samples. The molar absorptivity for the complexes at the wavelength of maximum absorption in the visible region, 371 nm is 2.75 × 103 L mol-1 cm-1. The method allows a reliable determination of fluoride in the range 0.3─3.0 mg L-1 which is compatible to WHO limit value of 1.5 mg L-1. The sensitivity, detection limit, quantitation limit, and correlation coefficient for the method were found to be 0.211 μg mL-1, 0.1 mg L-1, 0.3 mg L-1, and 0.9914 respectively. The percentage recovery of 1.5 mg L-1 fluoride is 101.3.