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

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 degrees 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+, Al3+, Ba2+, Ca2+, Cd2+, Co2+, Cu2+, K+, Mg2+, Na+, Ni2+, Pb2+) and anions (SO42-, SO32-, NO2-, I-, Br-, Cl-, SCN-, CH3COO-, H2PO4-, ClO4-) 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