Performance of arylboronic acids as ionophore for inorganic anions studied by fluorometry and potentiometry Original Research Article

Addition of fluoride at the 10−6 mol dm−3 level drastically reduced the fluorescence intensity of 1-naphthylboronic acid in dimethylsulfoxide. A PVC membrane electrode containing 1-naphthylboronic acid as an ionophore and tridodecylmethylammonium chloride as an additive showed a response to fluoride at concentrations of higher than 10−3 mol dm−3. The equilibrium analysis of the reaction of a related arylboronic acid [ArB(OH)2], phenylboronic, with fluoride in aqueous solution revealed that the following reaction is responsible for the fluorescence change and potentiometric response.ArB(OH)2+2H++3F−⇌ArBF−3 Use of cationic micelles enhanced the low reactivities of boronic acids in aqueous solution and enabled the fluorometric determination of fluoride at pH around 2. Iodide also could be determined by dynamic quenching of the fluorescence in neutral media.