Determination Of Fluorine Research Articles

Prompt nuclear analysis in thick samples with charged particles: The validity of Bragg’s law for range correction

The determination of fluorine in the fluorides of 31 elements by prompt analysis using the reactions (α, p0), (α, α1), (α, n1γ) and (α, p1γ) on19F was carried out in a search for discrepancies that could point to molecular effects in range corrections. Data for each reaction were normalised and normalisation factors were compared. The results for each compound were in good agreement, but intercomparison showed that the accuracy of stopping power data and the applicability of Bragg’s Law were acceptable within ±8%.

Determination of nitrogen and fluorine in air-dust samples by photon activation

Air-dust samples with masses of 12 mg each were analysed instrumentally for their nitrogen and fluorine content by photon activation. The samples were irradiated with photons of maximum energy,Emax=15MeV. The nuclear reactions14N(γ, n)13N and19F(γ, n)18F give two positron emitters. The positrons react with electrons, emitting annihilation radiation. The 511-keV peak of the annihilation radiation of13N and18F is measured simultaneously and the decay curve is taken. The half-lives of 9.96 and 109.7 min allow a quantitative separation. By choosingEmax=15 MeV for the activation we eliminate interference from carbon and oxygen. The activation threshold for the n,γ-reaction of carbon is 18.72 MeV and for oxygen 15.67 MeV, while the activation threshold for N is 10.55 MeV and for F 10.44 MeV. The detection limit for the instrumental method is 4μg for both nitrogen and fluorine.

Quantitative determination of boron and fluorine in presence of each other in organic and inorganic compounds

Es werden Methoden zur quantitativen Bestimmung von Bor und Fluor beschrieben, bei gleichzeitiger Anwesenheit beider Elemente in organischen und anorganischen Verbindungen. Nach Substanzaufschlus mit Hilfe bewahrter Methoden (Alkalischmelze oder thermisch) wird das Bor durch Destillation oder Mikrodiffusion als Methylborat abgetrennt und in Gegenwart von Mannit mit Natronlauge potentiometrisch titriert. Die Fluoridkonzentration wird mit Hilfe der fluoridsensitiven Elektrode gemessen. Nach thermischem Aufschlus (Schoniger, Wickbold) wird die alkalische Reaktionslosung zunachst zur Trockene eingedampft und durch Aufschmelzen Restmengen von Fluorborat, das sich sonst der Messung entzieht, in Fluorid und Borat umgewandelt.

The analysis of fluorine in geochemical exploration

Methods of measuring cold-extractable acid-diffusible and total fluorine are described together with a discussion of the ability of each method to attack fluorine-bearing minerals, their respective precisions and the various interferences affecting each technique. These three analytical methods can be used for the detection of a wide variety of mineral deposits containing fluorine. The choice of method or methods will be governed chiefly by the types of fluorine-bearing minerals associated with mineralization, the predominant type of dispersion in the secondary environment (hydromorphic or mechanical) and the obvious restrictions of cost and time. For greisens, pegmatites, non-fluorite-bearing disseminated deposits (mainly Nb, Ta, Sn, W, Be) and some placer deposits, cold-extractable methods will be unacceptable since fluorine occurs mainly in minerals resistant to this type of attack (tourmaline, topaz, pyrochlore, micas). The acid-diffusible method will produce adequate anomalies in stream sediments and soils associated with these deposits, only if a significant amount of the fluorine present is contained in the micaceous minerals or apatite. In most cases, the total method should be preferred for detecting these types of deposits. For kimberlites, and serpentinized ultrabasic and basic intrusions, in which fluorine occurs mainly in phlogopite, serpentine, apatite and various weathering products, the determination of cold-extractable and acid-diffusible fluorine will generally give lower anomaly contrasts than the total method. For deposits which contain a large amount of fluorite and/or apatite, such as carbonatites, some mesothermal and epithermal deposits, phosphate deposits and some pegmatite and disseminated deposits, cold-extractable and acid-diffusible methods will produce anomaly contrasts in soils and stream sediments similar to the total method. The application of all three of these analytical methods in an exploration program may be of value in understanding the forms in which fluorine is dispersed.

Sample fusion at low temperature for the potentiometric determination of fluorine in silicate materials

Sample fusion at low temperature for the potentiometric determination of fluorine in silicate materials

Determination of fluorine in urine and blood serum by aluminum monofluoride molecular absorption spectrometry and with a fluoride ion selective electrode.

Determination of fluorine in urine and blood serum by aluminum monofluoride molecular absorption spectrometry and with a fluoride ion selective electrode.

Determination of fluorine in zinc ores using an isotope neutron source based automated neutron activation analysis system

A method has been developed for routine determination of fluorine in zinc sulfide ores by activation with fast neutrons from a 6.6 Ci227Ac−Be isotope source and counting of the 4.5 to 7 MeV gamma-rays of the product nuclide16N. Samples and standards consist of pellets pressed from a mixture of powdered material with wax or graphite. Samples and standards alternate in a sequence of 20 seconds irradiation, 4 seconds decay and 20 seconds counting. This analysis sequence, including the computation of the analysis results from the counting data automated by means of a LSI-11 Microprocessor with 12K×16 bit memory. The zinc ores, containing 0.3 to 0.7% fluorine have been analysed with a precision ranging from 1.56 to 1.33% relative. As a test for the reliability of the method, three standard reference materials were analysed in the same way as the zinc ore samples.

The determination of fluorine in coffee and tea using a microprocessor coupled with a fluoride ion‐selective electrode

SummaryThe fluoride content of tea and coffee as normally brewed, and after Schöniger oxygen flask combustion, has been determined with a fluoride ion‐selective electrode coupled to a microprocessor analyser in two of its operational modes. Up to forty samples per hour can be assayed in the CONCN mode and the results compare favourably with the known addition (KA) back‐up mode.

Determination of Fluorine, Chlorine and Water in Eight USGS Reference Samples

Eight reference samples from the U.S. Geological Survey have been analysed for their contents of F, Cl and water. After pyrolysis F was determined with an ion‐selective electrode, Cl by colorimetry and water by Karl‐Fischer titration.

Determination of calcium, phosphorus and fluorine in bone by instrumental fast neutron activation analysis

The determination of fluorine, calcium and phosphorus in bone by instrumental fast neutron activation analysis is described. Results for the IAEA standard material “Animal Bone” A3-74 re: Ca=313±10 mg/g, P=155±5 mg/g and F-613±20μg/g. The accuracy for all three elements is≤4%, precision being about 3%. The limit of determination for F is 120 μg, for Ca 30 mg and for P 1 mg in a sample of 500 mg.

Accurate determination of lithium, boron, fluorine and sodium in some matrices using low energy alpha-particles induced gamma-rays

A method is described for analyzing some light elements with high accuracy. Prompt gamma-ray spectrometry with 3.5 MeV alpha-particles from a Van de Graaff accelerator was used: this technique is non-destructive, rapid and experimentally simple. Sensitivities are indicated and factors affecting the accuracy of analysis are considered. A range of different materials has been analyzed and analytical results are presented.

Microanalysis of Flourine by nuclear reactions: I. [formula omitted] reactions

The quantitative determination and depth profiling of fluorine in the surface region of various substrates using nuclear reaction microanalysis was studied. Differential cross sections and excitation functions for the reaction 19F(p, α 0) 16O and 19F(p, αγ) 16O were investigated in great detail, especially in the vicinity of resonances, where automatic energy scanning was used. Resonance widths and positions were measured precisely, in particular for the narrow resonances of 19F(p, αγ) 16O. A very narrow, τ = 150 ± 50 eV, resonance was found at 1088 keV. The excitation curves shown for various resonances allow one to carry out the computer calculations required for converting yield curves into depth profiles. The paper discusses how to choose among the nuclear reactions and resonances available to achieve best sensitivity, selectivity, depth resolution, ease of operation or speed of measurements, according to the problem considered, and to define the corresponding optimal experimental conditions. It appears that, in addition to the strong 872 keV, τ = 4.2 keV resonance of 19F(p, αγ) 16O, the 340 keV, τ = 2.4 keV resonance may be especially useful. The results are also of interest for hydrogen depth profiling when using the reverse reaction 1 H( 19 F, αγ) 16 O .

Computerized technique in organic microelemental analysis III. Automatic determination of fluorine in organic compounds

The automatic and computerized rapid microanalytical determination of fluorine in organic and organometallic compounds is an easily reproducible procedure. The procedure consists of the combustion of the compound in an empty tube; transfer of the combustion products to the titration vessel by automatic wash; and, finally, colorostatic titration of HF with Th(ClO 4), against alizarin red S. The entire analysis and preparation of the equipment for the next determination are programmed in the time of the 6-min cycle. The analyzer is interfaced to the departmental real-time time-sharing computer, along with electronic microbalances and other analyzers, as a part of the microanalytical laboratory computer service. Results of the analyses are reported on CR terminals and are also stored on the magnetic disk for further processing.

Trace determination of fluorine

Trace determination of fluorine

Rapid determination of fluorine in cements

Promt gamma rays from inelastic scattering and nuclear reactions induced by alpha particles have been used to determine fluorine in cements. The method is suitable for fluorine concentration of about 0.1% but is sensitive to parts per million. The precision of the method is determined by the homogeneity of the sample.

X‐Ray fluorescence analysis in the X‐ray region of 0.4 to 7 nm: Application to determination of fluorine in slags

AbstractX‐ray fluorescence analysis under high vacuum (∼10−6 torr) was applied to the determination of fluorine in slags. Slag samples are converted into glass beads using a fusion method and the fluorescent X‐ray intensity of characteristic X‐ray F Kα (1.83 nm) is measured to determine fluorine. The calibration curve has excellent linearity and accuracy; σd is 0.18% for 11 kinds of samples involving fluorine of 0.10% to 16.78% (mean: 6.96%).

Determination of fluorine by deuteron activation

A method has been developed for the determination the fluorine content from the induced activity of the short-lived nuclide20F (T-11.4 s; Eλ=1.63 MeV) formed by the reaction19F(d,p)20F. The method has been employed to determine fluorine in zirconium using a small-size 3 MeV deuteron accelerator for activation. The lower limit of fluorine detection is 0.5 ppm at the average deteron current of 0.3 μA.

Determination of fluorine in glasses by cyclic activation analysis using a californium-252 neutron source

A cyclic activation analysis method with a 100 μg252Cf source was developed for the determination of low concentrations of fluorine in glasses containing high concentrations of oxygen. Factors influencing errors in the analysis were investigated quantitatively. The activation cross-section of19F(n, α)16N for252Cf fission neutrons was determined. A brief description is given of the cyclic activation, analysis apparatus, and also the modified optimization of the cyclic operation. The usefulness of the analysis is demonstrated by application to a fluorine volatilization study.

Rapid general microdetermination of fluorine

A rapid micromethod for the determination of fluorine in a wide variety of materials has been developed. The method is based on the liberation of the fluorine (as HF) from the sample by means of pyrohydrolysis with steam at 1120° C, The amount of fluoride in the condensate is subsequently measured with an ion-selective electrode using a simple standard addition technique, which automatically compensates for variations in ionic strength, acidity, etc. Metals that may form stable complexes with fluoride are masked by the addition of a complexing agent to the condensate.

Comments on determination of fluorine in petroleum and petroleum process catalysts with a fluoride electrode

Comments on determination of fluorine in petroleum and petroleum process catalysts with a fluoride electrode