A spectrophotometric determination of fluoride adapted for the freshman laboratory

Abstract

Of the methods currently in use for determining the fluoride ion concentration in water, the electrode and colorimetric methods are believed to be the most satisfactory. We have devised a laboratory experiment for students in general chemistry based upon the SPADNS Colorimetric Procedure.1 The method is based upon the reaction of fluoride ion with a zirconium dye-lake. The ion reacts with the dye-lake to destroy it and form a colorless complex anion, (ZrF62~). As the concentration of the fluoride ion in the solution to be analyzed increases, the intensity of the color of the solution becomes progressively lighter. The intensity of the color is measured quantitatively with a spectrophotometer.

A new method for fluoride determination by using fluorophores and dyes anchored onto MCM-41Electronic supplementary information (ESI) available: IR spectra, SEM images, X-ray diffraction patterns and TG/TD analysis. See http://www.rsc.org/suppdata/cc/b1/b111128k/

“…See http:// www.rsc.org/suppdata/cc/b1/b111128k/ agreement with the claimed concentration has been found (see Table 1). It is noticeable that other colourimetric methods, such as the SPADNS Colourimetric Procedure for the determination of fluoride in toothpaste, 5 present serious deviations (even 67%) in solutions deliberately contaminated with pyrophosphate (P 2 O 7 42 , 0.32%), an anion that is usually present in toothpastes, meanwhile following the approach described here the determination of fluoride on samples containing a ten molar excess of phosphate with respect to fluoride gave errors of less than 8%.…”

“…Some colourimetric reactions for fluoride determination have been reported involving a recognition approach 3 or displacement reactions 4 , for instance the SPADNS colorimetric procedure in which fluoride is reacted with the Zr-SPADNS dye to form the colourless complex [ZrF 6 ] 22 . 5 The main inconvenience of these methods is the presence of important interferences as many anions compete with fluoride for the cation coordination and also many cations compete for the fluoride coordination.…”

“…5 The main inconvenience of these methods is the presence of important interferences as many anions compete with fluoride for the cation coordination and also many cations compete for the fluoride coordination.…”

Smartphone-based Fluoride-specific Sensor for Rapid and Affordable Colorimetric Detection and Precise Quantification at Sub-ppm Levels for Field Applications

“…However, water samples having higher turbidity and TDS > 2000 ppm can be pretreated by passing through a prefilter to get suitable sample for F – estimation. The dental care products were dissolved in water as per the reported procedure, and the resulting solutions were tested by the sensor device. , Before testing the samples, the device was calibrated and tested for various F – concentrations to check its accuracy which is shown in Figure A. Each of the samples were tested by keeping reaction time as 1 min.…”

Determination of a performance parameters of a spectrophotometer: An advanced analytic experiment.

“…The instrument that has been used is a G-CA-McPherson 707-D uv-visible spectrophotometer. An instrument with the following capabilities is required for the experiment: (1) It must be able to make absorbance measurements from 0-3 A, (2) It must be capable of scanning a spectrum at various rates with the slowest rate being about 1 nm/min, and (3) It must be capable of scanning at various resolutions. For the experiment to be of most value, the instrument should have other modern features such as baseline offset, full scale expansion, and digital display of absorbance.…”