Fluoride analyses

The most popular device for fluoride analysis is the ion-selective electrode (see Electro analytical techniques). Analysis usiag the electrode is rapid and this is especially useful for dilute solutions and water analysis. Because the electrode responds only to free fluoride ion, care must be taken to convert complexed fluoride ions to free fluoride to obtain the total fluoride value (8). The fluoride electrode also can be used as an end poiat detector ia titration of fluoride usiag lanthanum nitrate [10099-59-9]. Often volumetric analysis by titration with thorium nitrate [13823-29-5] or lanthanum nitrate is the method of choice. The fluoride is preferably steam distilled from perchloric or sulfuric acid to prevent iaterference (9,10). Fusion with a sodium carbonate—sodium hydroxide mixture or sodium maybe required if the samples are covalent or iasoluble. 

The JnitedSfates Pharmacopeia (76) specifications for sodium monofluorophosphate require a minimum of 12.1% fluoride as PO F (theoretical 13.2%) and a maximum of 1.2% fluoride ion reflecting unreacted sodium fluoride. Analysis for PO F is by difference between total fluoride ia the product less fluoride ion as determined by a specific ion electrode. The oral LD q of sodium monofluorophosphate ia rats is 888 mg/kg. 

Fluoride analysis requires a previous separation process step, which is known as Willard-Winter distillation using a mixture of HClOyH PO, to isolate fluoride from interferences like Al, Cl, etc. 

Evidence for a glycosyl-enzyme intermediate of finite lifetime with inverting a-D-glycosidases, and details of its reaction, came from studies with 2,6-anhydro-l-deoxyhept-l-enitols and glycosyl fluorides. - Analysis of hydration and hydrolysis products on the one hand, and of glycosyla-tion products on the other, indicated an intermediate that could be approached by water from the yff-face only of the ring, and by other glycosyl acceptors only from the a-face (see Schemes 4 and 5 This can be considered a proof of the principle of microscopic reversibility of chemical reactions. 

M. lijima, D.G.A. Nelson, Y. Pan, A.T. Kreinbrink, M. Adachi, T. Goto, Y. Mori waki, Fluoride analysis of apatite crystals with a central planar OCP inclusion Concerning the role of F" ions on apatite/OCP/apatite structure formation, Calcif. Tissue Int. 59 (1996) 377-384. 

D.R. Taves, Dietary intake of fluoride ashed (total fluoride) v. unashed (inorganic fluoride) analysis of individual foods, Br. J. Nutr. 49 (1983) 295-301. 

D. Osis, E. Wiatrowski, J. Samachson, H. Spencer, Fluoride analysis of the human diet and of biological samples, Clin. Chim. Acta (1974) 211-216. 

G.L. Vogel, C.M. Carey, L.C. Chow, J. Ekstrand, Fluoride analysis in nanoliter- and microliter-size fluid samples, J. Dent. Res. 69 (1990) 522-528. 

Certain precautions are observed in the fluoride determination to deal with contamination problems. The reagents and deionized water used are kept separate and used only for the fluoride analysis. Each new batch of water or reagent is analyzed for fluoride. Finally, the fluoride... 

Infrared spectroscopy - [ANALYTICALMETHODS - HYPHENATED INSTRUMENTS] (Vol 2) - [SPECTROSCOPY, OPTICAL] (Vol 22) -m fluoride analysis [FLUORINE COMPOUNDS, INORGANIC - INTRODUCTION] (Vol 11)... 

Laboratory analysis of drinking water may be required to assess possible fluoride excess in natural well waters and may also be necessary during incidents of failure of the equipment used to treat drinking water. The determination of fluoride in urine can be used to assess exposure to different sources of fluoride. For drinking water and urine, direct determination using a fluoride-specific electrode is employed. For food, feces, and tissue, prior separation of fluoride from the sample matrix is required using a Conway diffusion procedure. The combination of the fluoride-electrode with flow injection has allowed a rapid and sensitive method to be used for serum and urine fluoride analysis/ ... 

Halogens are determined by an Orion 901 ion analyzer using 94-09 fluoride, 94-17 chloride, 94-35 bromide, or 94-53 iodide electrodes. These determinations can be carried out sequentially on 1 aliquot of sample in the order chloride, bromide, iodide, and fluoride. Five M KNO3 used as the ionization buffer for the first three ions, while Orion "total ionic strength adjustor buffer" is used for fluoride analysis. All determinations are done by the standard additions technique. 

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