Spectrophotometric methods for the determination of fluoride ion usingindole-3-acetic acid interaction with iron(III)

Abstract

This study is related to the determination of fluoride ion by the conversion of pink-colored Fe(III) and indole- 3-acetic acid (IAA) into a colorless hexafluoride ferrite complex with the addition of fluoride. The optimum conditions of the complex formation were found to be pH 1.7 and a temperature of 60 °C. The maximum absorption wavelength of the complex and the detection limit of the method were 525 nm and 0.26 mg/L, respectively. The interfering effects of the different cations (Ag + , Al 3+ , Ba 2+ , Ca 2+ , Cd 2+ , Co 2+ , Cu 2+ , K + , Mg 2+ , Na + , Ni 2+ , Pb 2+) and anions (SO 2− 4 , SO 2− 3 , NO − 2 , I − , Br − , Cl − , SCN − , CH 3 COO − , H 2 PO − 4 , ClO − 4 ) were also investigated. The method was applied to standard and real samples and the resulting data were statistically compared at a confidence level of 95% with those obtained with the use of a fluoride-selective electrode.