Total Fluorine Analysis

One of the oldest methods in the literature for the measurement of organic fluorine compounds is the Wickbold method [125], where organic fluorine is converted to hydrogen fluoride via combustion. The Wickbold method is useful for determining the total organic fluorine content of a sample, but is nonspecihc and does not provide information on individual fluorinated molecules. In addition, for samples containing PFCs, the combustion may lead to incomplete decomposition and subsequent underestimation of the total fluorine content of the sample [125]. 

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Two contrasting IR spectroscopic techniques, ATR and photoacoustic spectroscopy, were investigated as means for the determination of fluorocarbon polymer finishes on wool fabric. Based on the experimental conditions used, the results of the photoacoustic spectroscopy method are more characteristic of the bulk sample, while the ATR results are more surface specific. Linear calibrations between polymer addition, as determined by total fluorine analysis, and the absorbance of the C-F stretching bands of the normalised spectral data were obtained for a typical commercial fluorocarbon polymer. The quantitative methods developed are used to help access the effects of wear and the subsequent heating of fluorocarbon polymer-treated fabric samples. 21 refs. 

M. Ponikvar, V. Stibiij, B. Zemva, Daiiy dietary intake of fluoride by Siovenian Military based on analysis of total fluorine in total diet samples using fluoride ion selective electrode. Food Chem. 103(2007) 369-374. 

The electrochemical results can be correlated with total fluorine contents obtained by elemental analysis and surface fluorine concentrations by XPS given in Table 4. 

Miyake, Y, Yamashita, N., So, M. K., Rostkowski, P, Taniyasu, S., Lam, P. K. S., et al. Trace analysis of total fluorine in human blood using combustion ion chromatography for fluorine a mass balance approach for the determination of known and unknown organofluorine compounds. J. Chromatogr. A, 1154 214-221 (2007). 

Total surface fluorine concentration values (pg F/cm2) were determined using neutron activation analysis. 

When performing the chemical analysis of an aqueous solution, we obtain a set of values representing the bulk concentration of dissolved components, but we do not discriminate the various forms of solutes in which a given species is partitioned. For instance, we can measure the total molal amount of calcium or fluorine mp, but this value is the sum of all partial molalities of ionic and... 

Sulfates are precipitated as BaS04, and then reduced with carbon at 1,000°C to produce CO2 and CO. The CO is either measured directly or converted to CO2 by electrical discharge between platinum electrodes (LonginelU and Craig 1967). Total pyrolysis by continuous flow methods has made the analysis of sulfate oxygen more precise and less time-consuming than the off-line methods. Bao and Thiemens (2000) have used a C02-laser fluorination system to liberate oxygen from barium sulfate. 

In 1935, the Committee was renamed the Analytical Methods Committee (AMC) but the main analytical work was carried out by sub-committees composed of analysts with specialised knowledge of the particular application area. The earliest topics selected for study were milk products, essential oils, soap and the determination of metals in food colourants. Later applications included the determination of fluorine, crude fibre, total solids in tomato products, trade effluents and trace elements, and vitamins in animal feeding stuffs. These later topics led to the publication of standard methods in a separate booklet. All standard and recommended methods were collated and published in a volume entitled Bibliography of Standard, Tentative and Recommended or Recognised Methods of Analysis in 1951. This bibliography was expanded to include full details of the method under the title Official, Standardised and Recommended Methods of Analysis in 1976 with a second edition in 1983 and a third edition in 1994. 

Thermal treatment reduced surface carbon on aminopropylsilane-treated fiber, presumably by desorbing adventitious material. Carbon from the organic substituent on the silane desorbed also, since the nitrogen present before thermal treatment was totally absent afterwards. (The wide scan analysis of heat-treated fibers is incomplete because small concentrations of sulfur, fluorine and phosphorus were present on this sample only. They are considered to be artifacts, deposited perhaps from the inner wall of the chromatographic column during ramping, and are not reported). 

Zuercher, F. 1981. Simultaneous determination of total purgeable organo-chlorine, bromine- and fluorine-compounds in water by ion-chromatography. In A. Bjorseth and G. Angeletti (eds), Analysis of Organic Micropollutants in Water, pp. 272-276. Dordrecht, Holland D. Riedel Publishing Company. 

Analysis.—Decomposition in aqueous alkali proved to be unsuitable analytical procedure for dioxygenyl hexafiuoroplatinate(v), giving consistently low values for fluorine. Platinum analysis required two determinations, one of the mixture of metallic platinum and hydrated platinum oxides, the other of the solution of hexafluoroplatinate(iv). The precipitate was reduced to the metal in hydrogen. Platinum in the solution was precipitated by zinc. The total-platinum figures were not very concordant and always higher than that required... 

Sensitivity of Electron Capture Ionization. We have found that negative ion LC/MS provides substantial increases in sensitivity as compared with positive ion LC/MS during analysis of fluorinated pyridines such as dithiopyr 1. An example of such sensitivity enhancement is shown in Figure 2. The top panel illustrates the total ion current trace obtained from injection of increasing amounts of dithiopyr in the positive ion mode with discharge ionization. 

Summary. We have shown that ion transport in "Nafion" per-fluorinated membrane is controlled by percolation, which means that the connectivity of ion clusters is critical. This basically reflects the heterogeneous nature of a wet membrane. Although transport across a membrane is usually perceived as a one-dimensional process, our analysis suggests that it is distinctly three-dimensional in "Nafion". (Compare the experimental values of c and n with those listed in Table 7.) This is not totally unexpected since ion clusters are typically 5.0 nm, whereas a membrane is normally several mils thick. We have also uncovered an ionic insulator-to-conductor transition at 10 volume % of electrolyte uptake. Similar transitions are expected in other ion-containing polymers, and the Cluster-Network model may find useful application to ion transport in other ion containing polymers. Finally, our transport and current efficiency data are consistent with the Cluster-Network model, but not the conventional Donnan equilibrium. 

NMR spectroscopy has also been used h)r elemental analysis. Tor example, it is possible to tnake accu-rale quaniiiaiive deierminaiions of total hydrogen in organic mixtures, Likewise, (he resonance of fluorine 19 can be used for the quantitative a alysi of that element in organic compounds--an analysis that is difli-cult (o carry out by classical methods. I or qiiantitaib e work, a low-rcsoluLion or wide-line spectrometer may he used. 

Further research indicated that a single-step digestion and derivatizadon could be accomplished using hydrofluoric add, avoiding dimer formation (700). The fluoride derivatives would be more volatile, which would help with the analysis of polar silanes. Applied to reversed-phase materials, the total percentage of carbon determine separately by the GC fluorination method and by elemental analysis was shown to agree to within 2% over the concentration range of interest. 

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