Direct Spectrophotometric Fluoride Determination.

Alizarin Complexone on Nanocrystalline TiO2: A Heterogeneous Approach to Anion Sensing

“…Alizarin complexone (AC) has been reported to be an attractive receptor molecule for solution based anion sensing, being highly sensitive to the presence of fluoride anions in buffered aqueous solutions in presence of lanthanide ions such as Ce III , [22,23] showing a bathochromic shift in the absorption bands in the visible region in the presence of this anionic analyte. [23] It has been established that carboxylate groups present in this molecule can ligate a wide range of metal ions, including Ce III , Ti III , Ti IV , Cu II , and Zn II , resulting in a strong orange coloration attributed to a ligand-to-metal charge-transfer absorption band.…”

A low-cost device for the estimation of fluoride in drinking water

“…The methods available involve a change in color on addition of water samples containing fluoride to solutions of (a) zirconyl-chloride octahydrate and sodium 2-(parasulfophenylazo)-1,8-dihydroxy-3,6-naphthalene disulfonate (SPADNS), (b) zirconyl-chloride octahydrate and 3-aliz- 9,10 arin sulfonic acid sodium salt (alizarin red S), 9 (c) ceric sulphate, and (d) cerium-alizarin complexone com-11 plex. 9,12,13 Because inexpensive light-emitting diodes (LEDs) and phototransistors are readily available, it is desirable that the addition of fluoride should cause a pronounced change in absorbance in the visible region. This would permit the use of a LED as a light source and a phototransistor as a detector.…”

“…However, it is an order of magnitude more expensive. In addition, the Ce-AC reagent solution (reagent A) is stable only for approximately 5 days, and the reaction time 13 required for testing is about half an hour. In contrast, the SPADNS reagent solution (reagent S) is stable for at least 2 years, 9 and the reaction time is negligible.…”

Fluoride Determination in Fluoridated Drinking Water

“…The alizarin complexan method was used as described by Yamamura et al (1962). Here the fluoride determinations were made without any prior purification of the samples.…”