Sodium fluoride extractant

Peek, D.C. and Volk, V.V., Composition and speciation of sodium fluoride extracted soil solution, Commun. Soil Sci. Plant Anal., 17, 741, 1986. 

A suspension of 17a,21-dihydroxypregna-4,9(ll)-diene-3,20-dione 21-acetate (0.77 g) and iV-bromoacetamide (0.3 g) in anhydrous methylene dichloride (40 ml) is added over 2-3 min with stirring to a mixture of anhydrous hydrogen fluoride (10.19 g), and anhydrous tetrahydrofuran (18 g) in a polyethylene bottle at —80° (acetone-dry ice). After 1 hr at —80° the reaction mixture is kept for a further 1 hr at 0° and then added cautiously to an excess of an ice-cold solution of sodium carbonate. Extraction with methylene dichloride and crystallization from acetone-hexane furnish 9a-bromo-ll -fluoro-17a,21-dihydroxypregn-4-ene-3,20-dione 21-acetate (0.69 g), mp 205-208°, raised by several crystallizations from acetone-hexane to 215-217° [aju 142° (CHCI3) max 240-242 mju (e 15,500). 

Note. Under the above conditions of determination the following elements interfere in the amount specified when the amount of Mo is 10 fig (error greater than 3 per cent) V, 0.4 mg, yellow colour [interference prevented by washing extract with tin(II) chloride solution] Cr(VI), 2 mg, purple colour W( VI), 0.15 mg, yellow colour Co, 12 mg, slight green colour Cu, 5 mg Pb, 10 mg Ti(III), 30 mg (in presence of sodium fluoride). 

After leaving the reactant zone, the product stream enters a 0.5 in diameter FEP tube cooled by either a salt-ice bath or acetone-carbon dioxide slush bath [16]. The gas mixture was scrubbed in a soda-Hme tower. Hydrogen fluoride was trapped by adding sodium fluoride to the reaction mixture or simply adding water. Then, the product solution was extracted with dichloromethane, washed with aqueous... 

Copaux-Kawecki An improved version of the Copaux process for extracting beryllium from beryl, which permits recovery of the fluorine. Addition of ferric sulfate to the dilute sodium fluoride solution remaining after the separation of the beryllium hydroxide precipitates sodium tetrafluoroferrate, which is then used in place of sodium fluorosilicate. 

A further spectrophotometric method [3, 4] for water soluble boron in soil, boron is extracted from soil with boiling water. Borate in the extract is converted to fluoroborate by the action of orthophosphoric acid and sodium fluoride. The concentration of fluoroborate is measured spectrophotometrically as the blue complex formed with methylene blue and which is extracted into 1, 2-dichloroethane. Nitrates and nitrites interfere they are removed by reduction with zinc powder and orthophosphoric acid. 

As indicated above, the crude product contains hydrogen fluoride. The sodium fluoride disposes of this by-product by the reaction NaF + HF — NaHF. An alternative procedure is to pour the crude product into water and to separate the product by extraction with pentane. 

Tetraalkoxy Tellurium Difluorides1 The required amount (0.16 mol) of alkanol and 90 g (2.1 mol) of dry sodium fluoride are placed in a 600-ml reaction tube. The tube is cooled in liquid nitrogen, evacuated to 0.001 torr, and 8.6 g (35.6 mmol) of tellurium hexafluoride are condensed into the tube, which is then sealed. The tube is allowed to warm to 20", then heated at 90° for 9 days, cooled, and opened. The mixture is extracted with chloroform, the extract is evaporated, and the residue is distilled under vacuum. 

Sodium fluoride, NaF.—The fluoride is precipitated on neutralizing hydrofluoric acid with the hydroxide or carbonate. It can also be prepared from cryolite,3 3NaF,AlF3, by removing the aluminium by treatment with excess of sodium hydroxide, and extracting the undissolved sodium fluoride with boiling water. 

For the fluorometric method, uranium is concentrated by co-precipitation with aluminum phosphate, dissolved in diluted nitric acid containing magnesium nitrate as a salting agent, and the co-precipitated uranium is extracted into ethyl acetate and dried. The uranium is dissolved in nitric acid, sodium fluoride flux is added, and the samples fused over a heat source (EPA 1980). 

Sodium fusion. About 0-3 g. of material in a gelatine capsule was placed in a Parr bomb, together with 0-2 g. of metallic sodium, all the operations being carried out in a dry-box. The bomb was heated for 1 hr. over a Meker burner, cooled, and opened at room temperature, and the excess of sodium was destroyed by boiling with absolute alcohol. Sodium fluoride was extracted from the residue with water and the fluorine determined as lead chloride fluoride (Found F, 32-7%). 

Aqueous samples are treated similarly beginning with the acidification step. The entire sample is then put through the hydrophobic resin, and the fulvic acids are eluted at pH 7. The humic acids are removed with 0.1 M NaOH (2). After extraction, purification of the samples can be accomplished by freeze-drying and dialysis. The use of strong acids and bases has been criticized for several reasons. They can promote degradation, decarboxylation, oxidation, and condensation reactions. Strong acids and bases can also dissolve siliceous materials and lyse cells, resulting in contamination of the sample. Other extractants have been proposed, such as sodium pyrophosphate or sodium fluoride however, the classical procedure offers the most complete dissolution of humic material from solid samples and is still most often used (72). 

Sodium Fluoride Tablets (0.5 mg) Sodium Fluoride Tablets (1.3 mg) Spironolactone Tablets (25 mg) Spirulina Extract Chewable Tablets... 

Procedures based on extraction with deionised water, dilute calcium chloride (0.01 M CaCl2) potassium chloride (1M KC1), saturated sodium fluoride (NaF) and hydrogen peroxide (H202) have been described. All procedures (except for H202 which ideally uses field-moist soil) are based on the use of air-dry soil of <2 mm particle size. No correction for water content is made when reporting pH results. The soil/solution ratio and the temperature of measurement should be noted on the report, as other soil/solution ratios are often used. These include saturation extracts and soil/solution ratios of 1 1 and 1 2.5. 

A technique for the separation of pertcchnetalc from mixed fission products by solvent extraction with TBP was described. The extraction was almost quantitative from a sulphuric acid solution. Sodium fluoride was used to provide the zirconium-niobium decontamination and a cation exchange column ensured the decontamination from metallic ions. Tc yields of 92 % were obtained [123. ... 

Solution NMR uses extracts of soils and environmental samples. As with any extraction procedure for soil organic phosphorus, there is always the risk of hydrolysis (Turner et aL, 2003b). There is little agreement on the most suitable extractant, but those in use include sodium hydroxide (Newman and Tate, 1980 Hawkes et aL, 1984), Bu NOH (Emsley and Niazi, 1983), the cation exchange resin Chelex in water (Adams and Byrne, 1989 Condron et aL, 1996), sodium hydroxide plus Chelex (Gressel et aL, 1996), sodium hydroxide plus sodium fluoride (Sumann et aL, 1998), and sodium hydroxide plus EDTA (Cade-... 

Prp4 is much more difficult and was obtained in early studies only be extracting sodium fluoride with anhydrous fluoric acid from complex compounds like Na2Prp6 (Soriano et al., 1966 Asprey et al., 1967). The products, however, were not free of impurities in most cases. The major breakthrough came from Spitsyn et al. (1974) who prepared pure PrP4 by solid state reaction of krypton difluoride with PreOn or Pr02 at room temperature ... 

In addition to activation by heparin, lipoprotein lipase requires the addition of cations and of a fatty acid acceptor such as serum albiunin (254). The enzyme is inhibited by high concentrations of NaCl (M), 5% sodium taurocholate and 5% protamine (376, 393), sodium fluoride and diethyl p-nitrophenyl phosphate (394), and polyamino acids (395). Particle-free extracts of human or rabbit spleen, kidney, and liver are also stated to be inhibitory (396). 

Fluoride in dentrifices is usually present as sodium fluoride or monofluoro-phosphate or tin(II) fluoride [192,313,341,358,359]. Analysis of aqueous extracts or slurries of such dentrifices take less than 10 min with the fluoride electrode and closely match those obtained by a diffusion—thorium(IV) titration method but which requires about 45 min per sample [358]. 

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