Fluorine determination

The analysis of a gas sample found 21.4 g of sulfur and 50.8 g of fluorine. Determine the empirical formula of this compound. 

K. Tsunoda, K. Fujiwara, K. Fuwa, Subnanogram fluorine determination by aluminum monofluoride molecular absorption spectrometry. Anal. Chem. 49 (1977) 2035-2039. 

There are many instances where hydrogen bonds formed between two electronegative atoms like oxygen or fluorine determine the stability and properties of crystals. When a... 

D. Grambole, C. Bauer, P. Gippner, C. Heiser, W. Rudolph, H.J. Thomas, Fluorine determination in the near surface region of solids using the 19F(p,p y)19F resonance reaction, J. Radioanal. Nucl. Chem. Articles 83 (1984) 107-115. 

J.R. Bird, E. Clayton, The PIGME method for fluorine determination, Nucl. Instr. Meth. 218 (1983) 525-528. 

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%). 

The homogeneity was verifled on intakes of 100 mg. Fluorine determinations were performed by addition of sodium carbonate, melting at 950°C for 30 min and final detection by Ion Sensitive Electrode. The results showed that the material is homogeneous at a level of 100 mg and above. 

In general, two methods are used to determine trace amounts of fluorine in different natural materials, fodder, and foodstuffs. These are photometric determination based on the reaction of fluoride ions with the lanthanum-alizarin complexing agent and electrochemical measurements of fluoride concentrations by means of F-selective electrodes (Brill 1995). When measuring fluorine in the fluids and tissues of mammals, it is pre-separated by distillation or diffusion. As applied to fluorine determination in plants, good results are demonstrated using alkaline hydrolysis with subsequent fluoride concentration measurements, or in an acid medium by means of ion-selective potentiometry (Galloway et al. 1975). 

The HDPE of fuel tanks contains small amounts of fluorine, determined as 0.3-1 g per 10 kg tank, incorporated as a sealant and present as polytetraethylene (PTFE). In Stage 2, to determine the effect of this fluorine, samples of fluorinated and unfluorinated tanks were sawn into small pieces and reground before being formed into injection-moulded test specimens for determination of torsion modulus, and of tensile, impact and ballistic properties. The thermal properties investigated were the degree of crystallinity, melting temperature, and flow characteristics. The measured properties were compared with those provided for in the relevant quality order for new material. 

Methods for determining fluorine-containing surfactants are not yet well developed. One approach is to perform a combustion and total fluorine determination on activated carbon used to adsorb surfactants from aqueous solution (24). 

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