Determination Of Fluorine Research Articles

The Application of Non-Analyte Spiking to the Average Stopping Power Approach for the Determination of Fluorine by PIPPS

Article The Application of Non-Analyte Spiking to the Average Stopping Power Approach for the Determination of Fluorine by PIPPS was published on January 1, 1992 in the journal Radiochimica Acta (volume 56, issue 1).

The elimination of matrix effects in the determination of fluorine by proton induced prompt gamma-spectrometry

By measuring the yield of prompt gamma-rays, induced by energetic protons, the ratio of the ranges in sample and standard was used in the average cross-section method to determine fluorine. By spiking the sample with known amounts of a lithium compound, a nonanalyte element (absent from the sample), the appropriate ranges in the samples were determined by measuring the prompt gamma-rays induced in the non-analyte spike. Fluorine was determined in ores and ivory and the method was tested by analyzing the standard reference materials SRM 91, SRM 120c and SRM 694.

Determination of light elements using cyclotron-accelerated particles

We present results on the determination of phosphorus, sulfur, fluorine and chlorine in various matrices and some consideration about the possbility of using fast neutrons in elemental analysis based on the variable energy U-120 Cyclotron of the Institute of Atomic Physics (IAP).

PIGME fluorine determination using a nuclear microprobe with application to glass inclusions

Fluorine quantitative microanalysis was performed on geological samples, using the 19F (p, p ′ γ) 19F reaction, with a 30 (μm proton microbeam at an energy of 3.4 MeV. We have detailed the analytical procedure and the calibration method in relation to a large range of fluorine concentrations in natural glasses and some minerals. This procedure was applied to study the fluorine distribution in melt inclusions trapped in minerals of different origins. The potential of this nuclear microanalysis method is discussed.

Determination of fluorine in solids down to 120 μg/g by wavelength dispersive X-ray fluorescence spectrometry

An X-ray fluorescence spectrometric method is described for the determination of fluorine from percent level down to 120 μg/g in fluoropolymers and in fluoride samples. The method is based on the measurement of the intensity of first order\(FK_{\alpha _{1,2} } \) line for 30 seconds using a flow proportional counter and a multilayer AXO6 crystal (2d=5.52 nm). The calibration curves of first degree base polynomials are linear over the concentration range of 8000–120 μg/g and of 48.92–76% measured. The precision and accuracy obtained for polymer samples in percent level of fluorine are up to ±≥0.5 and within ±≥1%, respectively. However, the precision (δ) for trace concentrations is in the range from 8 to 20%. In most cases the accuracy is up to ±7%, ±5% and ±4% in the concentration range of 120–8000 μg/g, 801–8000 μg/g and of 120–400 μg/g, respectively. The time needed to analyze one sample including calibration and regression analysis is about 8 minutes.

Analytical importance of some secondary and threshold reactions induced in nuclear reactors

The feasibility of threshold and secondary reactions as analytical alternatives for some special elements is discussed. Examples of applications, at the author's laboratory for determination of lithium, fluorine, titanium and thallium are presented. The importance of threshold reactions as interferences of capture reactions is also discussed. The pairs of elements where the interference was experimentally evaluated were calcium and titanium, scandium and titanium; manganese and iron; copper and zinc.

Determination of fluorine in urine and tap water by laser-excited molecular fluorescence spectrometry in a graphite tube furnace with front-surface illumination

Calculations of the coherent production of free pairs and of pair production with electron capture from ultrarelativistic ion-ion collisions are discussed. Theory and experiment are contrasted, with some conjectures on the possibility of new phenomena. 29 refs., 5 figs., 1 tab.

Evaluation of biological sample mineralisation methods for the determination of fluorine by graphite furnace molecular absorption spectrometry

Various mineralisation methods were evaluated as means of treating different liquid and solid biological samples for the determination of fluorine by the formation of aluminium monofluoride in an electrothermal graphite furnace and molecular absorption spectrometry (AIF-MAS). Simple sample dilution and the use of 0.01 M Al3+ + 0.01 M Sr2+ solution as a matrix modifier are sufficient to determine the fluorine content in most liquid samples, although some require the addition of 0.3 M ammonium nitrate to the matrix modifier solution in order to diminish background absorbance. In solid samples, treatment methods routinely used with fluoride ion-selective electrodes such as microdiffusion, furnace ashing - microdiffusion and oxygen flask combustion, were tested for compatibility with AIF-MAS. The results were compared with those obtained with a fluoride ion-selective electrode. The proposed mineralisation methods were checked for applicability to different plants, foodstuffs and other biological materials. Some of the methods gave an over-all precision of better than 10%, which is often acceptable, and all methods gave recoveries above 80%. Differences between labile + ionic fluoride and total fluorine can be established by sample treatment.

A trial of fluorine determination using the exoskeleton of Antarctic krill Euphausia superba.

A sensor for the determination of fluorine was constructed using an Ag-electrode and the exoskeleton of Antarctic krill from which endogenous fluorine had been previously removed. The principle of the proposed sensor is based on the membrane potential difference being pro-duced by the recombination of fluorine on the exoskeleton of Antarctic krill. A linear relationship was observed between the rate of the increase in the output of the sensor and the concentration of fluorine (0.5-5ppm) when the sample solution was stirred at 1000rpm and 25°C. Fluorine contents in raw and dried leaves of Japanese teas were determined by the proposed sensor and a conventional method. Good comparative results were obtained between the values determined by both methods. One assay could be completed within about 30min.

Fluorine Determination and Matrix Effects in DC and HF Hollow Cathode Discharges

Abstract The InF bands excited in a hollow cathode discharge have been used for fluorine determination in solid samples (containing from 10−6 to 10−1% F) and solutions (at the F− concentrations from 1 μg/ml to 1 mg/ml). The discharge operated at direct current (dc) or high frequency current (hf). A dependence of the InF band intensities on the fluorine concentration has been investigated. Matrix effects caused by some metals and halides have been studied and discussed.

Analytical characteristics of a multilayer dispersion element (2d = 60 Å) in the determination of fluorine in minerals by electron microprobe

AbstractThe analytical characteristics of a W/Si multilayer dispersion element (MLDE) with a nominal 2d spacing of 60 Å are assessed and compared with those of a conventional thallium acid phthalate (TAP) crystal for the determination of fluorine in silicate and phosphate minerals by electron microprobe. Measured count rates for fluorine were found to be up to fourteen times higher using the MLDE compared with TAP giving improved detection limits of 0.02 to 0.08 wt. % F (six sigma, 100s count time) compared with equivalent data of 0.06 to 0.12 wt. % F by TAP. At equivalent spectrometer angles, peak widths by MLDE were broader by a factor of 2 to 3. However, an important advantage of MLDE was found to be the absence of multiple order diffractions higher than the second order. In consequence, the troublesome third order P-Kα line interference on the F-Kα line, normally encountered in the analysis of apatites, is absent in determinations made using the MLDE. Conversely small interferences on the F-Kα line were detected from the first-order Lα line of Fe and second-order Lα line of Mg. X-ray data and spectra of selected minerals are presented to demonstrate these interferences. Detection limits for elements that can also be determined using the MLDE were 0.07 to 0.15 wt. % oxygen and 0.34 wt. % carbon.

New studies of the plasma emission detector

Being an element-selective detector, the plasma emission detector was used to determine carbon in organic compounds. Experiments were carried out with the aid of osculating interference filters and lock-in amplifiers. The obtained signals were processed by a fast-Fourier-transform analyzer to study their frequency spectra. Results are given for the detection of carbon. Furthermore studies on the influence of angle-adjustment, microwave power, photomultiplier voltage and oscillation frequency on the determination of fluorine in organic compounds were carried out and results for detection limits and dynamic range of this method are presented.

RAPID NON‐DESTRUCTIVE DETERMINATION OF FLUORINE IN SEVENTY‐ONE GEOLOGICAL AND OTHER REFERENCE SAMPLES USING FAST‐NEUTRON ACTIVATION ANALYSIS

The fluorine concentration in seventy‐one reference samples of geological interest has been determined using fast‐neutron activation analysis. The reaction involved [19F(n, α) 16N] uses accelerator‐derived neutrons produced by bombarding a Be target with 3 MeV deuterons. The gamma radiation associated with the decay of 16N (t1/2 = 7.13 s) is counted and for the irradiation conditions used there are no serious interferences. The advantages of this technique over other schemes of fluorine determination are its simple procedure for sample preparation, speed, high sensitivity and non‐destructiveness. A comparison of the data obtained with those in the literature is highly favourable.

Inter-laboratory note. Chemical generation of silicon tetrafluoride with direct current plasma atomic emission spectrometry for the determination of fluorine

A method is described for the determination of fluorine in aqueous samples via the chemical generation of silicon tetrafluoride. The generated vapour was swept to a direct current plasma and silicon measured by atomic emission spectrometry. The detection limit obtained for fluorine was 0.9 µg ml–1 for a 100-µl sample.

Determination of fluorine in glass crystallite using complexometric back titration

Determination of fluorine in glass crystallite using complexometric back titration

Determination of fluorine and chlorine in geological materials by induction furnace pyrohydrolysis and standard-addition ion-selective electrode measurement

Fluorine and chlorine in geological materials are volatilized by pyrohydrolysis at about 1150° in a stream of oxygen (1000 ml/min) plus steam in an induction furnace. The catalyst is a 7:2:1 mixture of silica gel, tungstic oxide and potassium dihydrogen phosphate. The sample/catalyst mixture is pyrohydrolysed in a re-usable alumina crucible (already containing four drops of 1 + 3 phosphoric acid) inserted in a silica-enclosed graphite crucible. The absorption solution is buffered at pH 6.5 and spiked with 1.6 μg of fluoride and 16 μg of chloride per g of solution, to ensure rapid and linear electrode response during subsequent standard-addition measurement. The simple plastic absorption vessel has ⪢99.5% efficiency. The 3 s limits of detection are 5–10 μg/g and 40–100 μg/g for fluorine and chlorine respectively. The procedure is unsuitable for determining chlorine in coal.

Fluorine determination in hamster tooth germs

The delayed 5 2 + → 1 2 + nuclear transition of fluorine ( E γ = 197 keV, t 1 2 = 87 ns ) emitted after the 19F(p,p′ γ) 19F reaction, has been used to measure the influence of fluoride administration on tooth development in vivo. The method used has the advantage of an improved peak to background ratio for the detection of fluorine if measurements are performed anticoincident with the cyclotron burst. Besides the registration of fluoride distributions, also bulk elements like P and Ca have been measured to correlate the detected fluorine distributions with some specific morphological structures in hamster tooth germs.

Determination of Fluorine in Geological Material by Photon Activation and Radiochemical Separation

The determination of fluorine in geological material by photon activation analysis based on the 19F(γ, n)18F reaction is described. After irradiation fluorine is separated by steam distillation of hexafluorosilicic acid and precipitation as CeF3. Labelling of the cerium reagent solution by 141Ce enables a simple correction of separation losses. The method was applied to the ZGI standard rock granite GM.

Application of helium microwave-induced plasma mass spectrometry to the detection of high ionisation potential gas phase species

The determination of fluorine, chlorine, bromine and iodine as positive ions is accomplished using a helium microwave-induced plasma (MIP) as an ion source for quadrupole mass spectrometry. A helium MIP sustained in an internally tuned TM010 cavity is interfaced to a commercially available mass spectrometer for the detection of the aforementioned halogens as positive ions. The mass spectral background of the helium MIP and the effect of plasma sampling parameters on the background are discussed. Detection limits for Cl+, Br+ and l+, from the methyl halogens, are estimated to be at picogram levels or lower.

Determination of total fluorine in vegetables and plants by open-flame ashing and microdiffusion : Comparison with furnace ashing and oxygen-flask combustion

The sample is ashed in a nickel crucible over an open flame with calcium hydroxide as the fixative; fluoride is separated by micro-diffusion and measured with a fluoride-selective electrode. The calcium hydroxide fixative permits a temperature of 800–850°C during the final ashing, so that insoluble silicates are decomposed and fluoride is converted to an acid-soluble form. Other advantages over furnace ashing at 600°C are less contamination and more rapid ashing (20 min compared to 6 h). The interference of aluminium and silica on microdiffusion was studied: perchloric acid was found to be preferable to sulphuric acid as medium. A new way for preparing calcium hydroxide suspension, low in fluoride, is described. The values found by the proposed method generally compare well with those obtained by oxygen flask combustion. Direct diffusion (i.e. without ashing) gave much lower values than the ashing methods, except for tea leaves.