Spectrophotometric determination of fluoride in aqueous solution using 2-hydroxy-1-(2-hydroxy-4-sulfo-1-naphthyl azo)-3-naphthoic acid

Abstract Fluoride (5–70 μg) in a final volume of 100 ml was determined. The analysis was based on the colored reaction of Al-HHSNNA and the bleaching effect of fluoride on it. The method is simple and rapid, and the accuracy is satisfactory when applied to different types of water. The procedure compared favorably with the conventional colorimetric method (D. F. Boltz and J. A. Howell (Eds.), Colorimetric Determination of Nonmetals , 2nd ed., pp. 10, 128, 1978). It is worth noting that the introduction of alizarinfluorine blue in 1958 and the pF electrode in 1966—both of fundamental importance—cannot be ignored in the introduction of the present method for fluoride as these still hold.