Determination Of Fluorine Research Articles

The radioanalytical laboratory at Pelindaba. Some applications for environmental and health monitoring.

This article deals with the radioanalytical work performed at Pelindaba, Atomic Energy Corporation of South Africa. It reports on the activities of a commercial laboratory, employing analytical techniques, such as total alpha/beta counting, alpha spectrometry, liquid scintillation counting, gamma spectrometry, and neutron activation analysis. Techniques discussed in more detail include semicyclic activation analysis for the determination of fluorine in vitamin mixes, as well as the determination of uranium and radium in urine samples for personnel monitoring.

The determination of tin, chlorine, and fluorine in six japanese sedimentary standards

Concentrations of tin, chlorine, and fluorine in six new Geological Survey of Japan (GSJ) sedimentary standards are reported. Tin was determined using graphite furnace atomic absorption spectrometry (GFAAS), following a lithium metaborate (LMB) fusion of the rock material. Chlorine and fluorine were determined using ion-selective electrode (ISE) potentiometry following an acid digestion and a LMB fusion, respectively. The methods employed are briefly described and determination limits in the rock of 0.2 μg/g for tin, 10 μg/g for chlorine, and 100 μg/g for fluorine are reported. The precision obtained for the six sedimentary standards, expressed as %relative standard deviation, averaged 5.3% over the range of 2-200 μg/g tin, 5.8% over the range of 20–65 μg/g chloride, and 1.7% over the range of 100–4500 μg/g fluoride, all in the rock. This compares favorably to the precision obtained for international geologic reference materials determined concurrently with the GSJ sedimentary standards. The values of tin, chloride, and fluoride obtained for the international reference materials were in favorable agreement with the recommended literature values.

Determination of fluorine in biological materials: a review.

This review on determination of fluorine in biological materials briefly covers (a) a discussion of various forms of fluorine in body fluids and tissues [and also in foods]; (b) methods of their determination, including pretreatment of samples, separation and concentration of F and its final measurement; (c) an evaluation of the analytical methods used and interpretation of results; and (d) some recommendations for future research in fluorine analytical methods applicable to biological materials.

Determination of oxygen, fluorine and boron by 14-MeV INAA: A case of multiple interferences

Oxygen and fluorine have been simultaneously determined by 14-MeV INAA in samples containing boron. Both boron and fluorine can cause serious interferences in the determination of oxygen. The fluorine and boron interference corrections for oxygen determination have been determined to be 0.43±0.01 and 0.0832±0.0017 apparent g oxygen per g of fluorine and boron, respectively, for our system. Boron can be determined in the same sample by a second irradiation. Mutual interferences have been evaluated and the procedure has been applied to NIST SRM and several other compounds.

On the use of LiF as non- and analyte spike for the determination of fluorine by PIGE

By spiking the sample and analyte standard with a compound containing a common non-analyte element, to which a relative deceleration property for 5 MeV protons has been ascribed to, relative deceleration values for these target materials could be obtained by PIGE. These values are used to correct for matrix effects in elemental analysis using PIGE techniques. A simplification of this analytical procedure has been achieved by the selection of a spiking compound containing both the non- and analyte element. Now, with the spike also being the analyte standard, the need for additional comparators and the spiking thereof are eliminated. In addition to this advantage, the analytical results thus obtained can also be compared to those obtained by the simultaneous application of the analyte spiking technique to the collected yield data. A comparison of these non- and analyte spiking approaches was made by analyzing the standard reference materials SRM 694, SRM 120c, SRM 91 and SARM 32. LiF, containing both the non- as well as the analyte element, was selected as comparator and spike.

Certified reference materials for the quality control of fluorine in coal, fly ash and clay

A group of laboratories has worked in various intercomparisons in the frame of the BRC-programme (European Commission) to improve their methods for fluorine determination, especially for coal analysis. These exercises allowed to detect and remove sources of error. Methods were improved to such an extent that the certification of fluorine and chlorine in different materials could be envisaged and the BCR consequently decided to produce coal, fly ash and clay materials certified for their F content. In addition, chlorine was certified in the fly ash CRM.

Complexometric Determination of Aluminium and Fluorine after Separation of Aluminium on TBP-Plasticized Polyurethane Foam

Simple titrimetric methods have been described for determination of aluminium and fluorine after selective separation of aluminium from fluorine using TBP-plasticized polyurethane foam sorbents. The extraction of aluminium from 0.20 to 0.30M NaOH solution has been found to be quantitative at 25°C. The sorbed aluminium complex can be eluted with 1M HC1 and determined titrimetrically at pH ∼ 5.3 with EDTA by the back titration method using xylenol orange as indicator. Fluorine left in the aqueous part has been determined titrimetrically with standard thorium nitrate solution in presence of 40% acetone at pH 3.0 ± 0.2 using sodium alizarin sulphonate as indicator. Anions like—PO43-, SiO32-, AsO32-, VO3−, CrO42-, BO33-, MnO42-, MnO4− and GaO2−″ have no effect on the extraction of aluminium as well as on the determination of fluorine. Both the methods have been standardised against standard samples.

Role of barium chemical modifier in the determination of fluoride by laser-excited molecular fluorescence of magnesium fluoride in a graphite tube furnace

Some improvement in the determination of fluorine in urine and tap water by use of laser-exicted molecular fluorescence spectrometry of magnesium monofluoride in a graphite tube furnace has previously been reported. The use of barium as a chemical modifier increased the size of the signal by a factor of 100. The work reported in the present paper was carried out in an attempt to elucidate the mechanism of the enhancement of the magnesium fluoride fluorescence by barium, and to explain some other experimental characteristics of the method, such as the vaporization temperature, which was lower at 1800 °C than the 2400–2700 °C reported by other workers. The mechanism of formation of gaseous magnesium fluoride molecules from sodium fluoride and magnesium nitrate solutions in a graphite tube furnace during atomic absorption measurements was investigated with and without the presence of barium. It was shown that, without chemical modification, the formation of magnesium fluoride in the gaseous phase proceeded mainly via interaction between magnesium difluoride molecules and excess of free magnesium atoms [Mg(g)+ MgF2(g)→ 2MgF(g)]. The efficiency of this process was fairly low, primarily because of the difference between the vaporization temperatures of the reacting species (1400 °C for magnesium difluoride and 1800 °C for magnesium vaporized as magnesium oxide). The presence of barium changed the mechanism of formation of magnesium fluoride. It was calculated that the formation of barium difluoride, rather than magnesium difluoride, was thermodynamically preferable in the first step of the mechanism. Experimental data indicated that the formation of magnesium fluoride then proceeded with higher efficiency than without barium because the reaction Mg(g)+ F(g)→ MgF(g) followed the appearance of magnesium from magnesium oxide, and fluorine from barium difluoride at coincidental temperatures in the range 1700–1900 °C.

Content of fluorine in vegetables and fruits from an industrial area

Content of fluorine in vegetables and fruits from allotments situated in an industrial area as well as in an agricultural area without industrial emissions was determined. The fluorine determination was made by means of a potentiometric method with application of an ion-selective electrode. Statistically significant differences between the fluorine content in vegetables and fruits from an area contaminated with the emissions of fluorine compounds and the fluorine content in vegetables and fruits from the control area were found. Significant differences between the fluorine content in above- and under-ground parts of some vegetables were stated. The greatest fluorine content appeared in parsley haulm and in black currants.

Determination of Fluorine, Chlorine, and Bromine by Molecular Absorption Spectrometry

Fluorine was determined by molecular absorption spectrometry (MAS) in a graphite tube furnace, and fluorine, chlorine, and bromine were determined in a flame. For the fluorine work, aluminum nitrate was added as a reagent to produce aluminum fluoride molecules whose absorbance was monitored with emission from a platinum hollow cathode lamp (HCL) at 227.45 nm. A deuterium arc lamp was employed for background correction. For the furnace work, barium nitrate was used as a chemical modifier to increase the absorption signal. After optimization of the chemical and furnace conditions, a detection limit of 160 pg F was obtained, with a linear dynamic range of two orders of magnitude. Graphite furnace MAS was used to accurately determine fluoride in dental rinse and National Institute of Standards and Technology oyster tissue, but the precision was between 21 and 23%. Low recoveries were obtained for the determination of trifluoroacetic acid and l,2,2,3-tetrafluoropropan-1-ol by graphite furnace MAS. The detection limit for F by flame MAS was 13 mg liter −1 which is a factor of 5 lower than the best reported flame MAS detection limit. Chlorine was determined by flame MAS with the aluminum chloride molecule. Excitation was done at 261.4 nm with a lead HCL. and a detection limit of 180mg liter −1 was obtained. Flame MAS of bromine was done by use of AlBr (excitation at 279.0 nm with an arsenic HCL) and InBr (excitation at 284.3 nm with a chromium HCL), but very poor detection limits were obtained: 24.5 g liter −1 and 500mg liter −1, respectively.

An equipment for the on-line determination of the fluorine, silicon and barium content of fluorspar and baryte ores

A new version of the automatic activation technique for the determination of fluorine, silicon and barium in fluorspar and barytes using an isotopic neutron source is presented. The main components of the automatic equipment consist of a sampling device and a “one-chamber” irradiation and measurement part with source transfer between the irradiation and the neutral position of source. The results of the measurements are proved to be best suited for the control of the flotation process under industrial conditions.

Determination of Organic (Covalent) Fluorine in Blood Serum by Furnace Molecular Absorption Spectrometry

This technique is an alternative approach to the previously described sodium biphenyl-reverse extraction-AIF molecular absorption spectrometric procedure for determination of organic fluorine in blood serum. The reverse extraction step for separation of fluoride from aqueous extracts, following cleavage of the CF covalent bond with sodium biphenyl, has now been replaced by the calcium phosphate adsorption technique. The overall procedure is now far less labor intensive and slightly more rapid than before. Recoveries of 0.02, 0.04, and 0.06 μg F in 20 μl serum samples are 100%. The results obtained by the new and previous procedures are similar. Several hundred blood samples have been successfully analyzed by the new procedure.

Separation of fluoride ion by extraction with triphenyltin chloride. Application for NAA of fluorine by means of 14-MeV neutrons

The separation of fluoride by extraction with toluene solution of triphenyltin chloride has been studied. Quantitative isolation of fluoride from solutions with a wide acidity range (pH 4.0–11.5) has been established. It is suggested that interferences by Ca, Mg, Fe, and Al can be avoided by masking these elements using sulfate and hydroxyde ions. Interference by phosphate ions can be overcome in a similar fashion. The halogenated species can be masked by mercury nitrate. Detection limit for fluorine determination is about 3 μg for a neutron generator flux of 2·1111 n·cm−1·s−1. A method for fluorine assay in water using a neutron generator with a detection limit of 1 ppm has been developed.

Quantitative determination of fluorine in toothpastes

AbstractThe quantitative CE analysis of fluorine and monofluorophosphate in toothpastes is described. Separation is performed using a Waters CIA‐Pak chemistry kit with Waters Electro Osmotic Flow Modifiers on a CE instrument from Spectra Physics (Spectra‐phoresis 500) at elevated temperatures up to 40 °C and at a low temperature of 10 °C. The quantitative results and the simplicity are compared for the CE method, the existing standard GC procedure described in the Official Journal of the European Communities, and the procedure employing a fluoride‐ion‐specific electrode.

Determination of fluorine and iodine in biological materials

Fluorine and iodine were determined in some biological reference materials. Radiochemical neutron activation analysis was used for iodine and ion-selective potentiometry for fluorine. The two elements were separated from the matrix elements by pyrohydrolysis in the presence of vanadium(V) oxide. The volatile compounds were absorbed in sodium hydroxide solution for the determination of fluorine and in acidic silver nitrate solution for the determination of iodine. This method gives low detection limits with small sample sizes.

Ascribing Relative Deceleration Properties to the Non-analyte Spike for the Determination of Fluorine by PIPPS

Article Ascribing Relative Deceleration Properties to the Non-analyte Spike for the Determination of Fluorine by PIPPS was published on February 1, 1993 in the journal Radiochimica Acta (volume 60, issue 2-3).

Preparation of fluoroborato-fluorophosphate glasses

A new family of fluorinated glasses was obtained based on the system KBF 4NaPO 3, NaFBaF 2KBF 4NaPO 3 and NaFB 2O 3NaPO 3. For fluorine enrichment of the glasses, two different agents were used: NH 4HF 2 and NH 4BF 4. The determination of fluorine in the prepared glasses demonstrates that NH 4BF 4 is an excellent fluorinating agent, the increase of fluorine content being the same as in the case when NH 4HF 2 was used. Possible structural models were established from the IR spectra of the glasses. Incorporation of fluorine in the borato-phosphate framework induces a coordination change to tetrahedral boron with the formation of oxyfluoroborate species, and also destroys the phosphate structure inducing the formation of shorter chains with fluorinated terminating groups.

Fluorine determination in diet samples using cyclic INAA and PIGE analysis

Fluorine is an important trace element for life and human well-being. Food, in general, provides about 40 percent of the fluorine intake in the human body. In order to measure fluorine levels in human diet samples, Instrumental Neutron Activation Analysis (INAA) and Proton Induced Gamma-ray Emission (PIGE) analysis were used. Reactions19F(n,γ)20F and19F(n, p)19O were employed for determination of the fluorine concentration using a reactor neutron spectrum and epithermal neutrons. Corrections were made for the sodium matrix interference caused by the23Na(n, α)20F threshold reaction in the case of reactor neutron cyclic activation analysis and for the oxygen interference via18O(n, γ)19O reaction when using the epithermal cyclic NAA method. The fluorine content of the diet samples was also determined by PIGE analysis making use of the resonance reaction19F(p, αγ)16O at 872 keV. Cyclic Neutron Activation Analysis (CNAA) when combined with mass fractionation was found to be the most suitable for determination of low concentration of fluorine, through the19F(n, γ)20F reaction with a detection limit of 2.2 ppm in Bowen's Kale elemental standard.

Application of short time activation analysis in the sciences

Short time activation analysis was applied to the analysis of reactor emergency poisoning solutions, to the analysis of doping elements in small organic semiconductor specimens, for the analysis of high temperature superconductors, and the determination of fluorine in various materials including biopsy samples. All the halogens in waste water were analyzed by a single 20s activation followed by two successive counting periods of 20 and 200s.

Test of a new standard for fluorine determination with PIGE

The flourine concentration of chemically enriched hydroxylapatite (Ca10(PO4)6(OH)2) was measured by means of PIGE using the nuclear reactions 19F(p,p'γ)19F and 19F(p, αγ)16O. The experiments were done in two runs with 1.68 and 2.15 MeV proton incidence. The results determined with inelastic scattering are in good agreements in the two runs. The samples are suiotable as new fluorine standards in teh ppm region to study the fluorine content in tooth enamel.