Determination Of Fluorine Research Articles

Fluorine Mass Balance and Suspect Screening in Marine Mammals from the Northern Hemisphere.

There is increasing evidence that the ∼20 routinely monitored perfluoroalkyl and polyfluoroalkyl substances (PFASs) account for only a fraction of extractable organofluorine (EOF) occurring in the environment. To assess whether PFAS exposure is being underestimated in marine mammals from the Northern Hemisphere, we performed a fluorine mass balance on liver tissues from 11 different species using a combination of targeted PFAS analysis, EOF and total fluorine determination, and suspect screening. Samples were obtained from the east coast United States (US), west and east coast of Greenland, Iceland, and Sweden from 2000 to 2017. Of the 36 target PFASs, perfluorooctane sulfonate (PFOS) dominated in all but one Icelandic and three US samples, where the 7:3 fluorotelomer carboxylic acid (7:3 FTCA) was prevalent. This is the first report of 7:3 FTCA in polar bears (∼1000 ng/g, ww) and cetaceans (<6–190 ng/g, ww). In 18 out of 25 samples, EOF was not significantly greater than fluorine concentrations derived from sum target PFASs. For the remaining 7 samples (mostly from the US east coast), 30–75% of the EOF was unidentified. Suspect screening revealed an additional 37 PFASs (not included in the targeted analysis) bringing the total to 63 detected PFASs from 12 different classes. Overall, these results highlight the importance of a multiplatform approach for accurately characterizing PFAS exposure in marine mammals.

Mixed Ligand Complex of Lanthanum(III) and Alizarine-Complexone with Fluoride in Micellar Medium for Spectrophotometric Determination of Total Fluorine

Mixed Ligand Complex of Lanthanum(III) and Alizarine-Complexone with Fluoride in Micellar Medium for Spectrophotometric Determination of Total Fluorine

Correction: Determination of fluorine in copper ore using laser-induced breakdown spectroscopy assisted by the SrF molecular emission band

Correction for ‘Determination of fluorine in copper ore using laser-induced breakdown spectroscopy assisted by the SrF molecular emission band’ by Zhiyang Tang et al., J. Anal. At. Spectrom., 2020, 35, 754–761, DOI: 10.1039/C9JA00407F.

Determination of fluorine in copper ore using laser-induced breakdown spectroscopy assisted by the SrF molecular emission band

The SrF molecular band as an alternative to the fluorine atomic line was proposed to detect fluorine in copper ore using LIBS technology in air.

Development of a method for the direct determination of fluorine in solid samples using electrothermal vaporization coupled to inductively coupled plasma optical emission spectrometry

ETV-ICPOES in atomic emission mode allows the direct determination of as low as 30 μg kg−1 fluorine in solid samples.

Determination of fluorine by total reflection X-ray fluorescence in fluoride fluxes

Total reflection X-ray fluorescence spectrometry (TXRF) is known as a state-of-the-art and fast-growing analytical technique. The spectral range of TXRF spectrometry encompasses elements from sodium to uranium. The object of this study was to develop, optimize, and validate the analytical method for fluorine in a form of calcium fluoride determination in fluoride fluxes by total reflection X-ray fluorescence spectrometry. The sample was lixiviated in acetic acid, then, the sample was filtered and the sediment and the filter were ignited at 650 °C. A portion of dried and ignited and weighed sample was placed in a plastic centrifuge tube. To this tube Triton X-100, Ga as internal standard and polyvinyl alcohol were added. The accuracy of the element determinations was estimated by comparison between obtained and certified values of the elements determined in the Certified Reference Materials of fluorite (fluorspar). The limit of detection for TXRF measurement is 4.26 μg F · dm−3 whereas the limit of quantification equals 12.78 μg F · dm−3. The variation coefficient that characterized the reproducibility of the measurement equals 16.94%. In addition to this, it was found that the uncertainty of results associated with the sample preparation process for TXRF measurement is negligible, compared to the measurement uncertainty at the measurement stage using TXRF spectrometry. The results of this work demonstrate the acceptable and fully satisfactory validation criteria such as limit of detection and quantification, accuracy, and precision.

A simple, rapid, green and non-destructive 19F time-domain NMR method for directly fluorine determination in powder of mineral supplements for cattle

A simple, rapid, green and non-destructive 19F time-domain nuclear magnetic resonance (TD NMR) method for fluorine determination directly in the powder of cattle mineral supplements is presented. The measurements were performed in a 0.49 T (18.76 MHz for 19F) spectrometer using a 10 mm probe with 10 μs dead time. Standard samples from 0 to 21,700 mg kg −1F were prepared diluting the appropriate amount of BaF2 in the salts Na2CO3: NaCl (1:1 w/w) that are normally used in the mineral supplements. The intensity of the free induction signal (FID), measured at 10 μs after 90° pulse and the fluorine content was used in an univariate model, with a limit of detection of 388 mg kg−1F. A partial least square model was also built using all FID data points and Fluorine content and yield a standard error of validation of 199 mg kg−1F. Accuracy was assessed by addition / recovery tests the analysis for two mineral supplements for cattle with trueness from 81 to 120%. Therefore, this is a green (non-chemical waste), simple (minimal sample preparation), fast (20 min) alternative method for determination of F in cattle mineral supplements.

Crystal structures, Hirshfeld surface analysis and Pixel energy calculations of three trifluoromethylquinoline derivatives: further analyses of fluorine close contacts in trifluoromethylated derivatives

Abstract As many studies have revealed, the introduction of a CF3 group into an organic compound can result in significant enhancement of biological activity. Factors which lead to this enhancement are thus of great interest. To investigate further this area, we have looked at the ability of fluorine to form close contacts with various atoms in organic compounds, e.g. F⋯F, F⋯O/O⋯F, F⋯C/C⋯F, H⋯F/F⋯H, and F⋯N/N⋯F, as indicated from crystal structure determinations and Hirshfeld analysis studies on trifluoromethylated compounds. Herein we first report the crystal structures, Hirshfeld surface analyses (HSA), and Pixel energy calculations of three trifluoromethylated quinoline derivatives, namely 2-(trifluoromethyl)quinolin-4-ol, 1, 4-ethoxy-2-(trifluoromethyl)quinoline, 2, and N 1-(2,8-bis(trifluoromethyl)quinolin-4-yl)ethane-1,2-diamine, 3. Of particular interest is the determination of the various fluorine⋯atom close contacts. The total percentages of fluorine⋯atom close contacts in compounds 1–3 were determined to be high at 47, 41.2 and 60.7%, respectively. As relatively few HSA studies on trifluoromethylated compounds have reported the percentages of individual atom⋯atom close contacts, we have also determined the percentages of atom⋯atom close contacts for 20 more trifluoromethylated compounds: the range of total fluorine⋯atom close contacts for these compounds was 20–60%. While these data are based on connections between similar molecules in a crystalline state, they also clearly suggest that a compound containing CF3 group(s) has the potential to make extensive intermolecular connections/close contacts with organic material. Thus a possible factor for the enhanced biological activity of a compound bearing CF3 group(s) could be the propensity of the CF3 group to form many close contacts, thereby aiding binding or interaction with a biological target.

The use of high resolution graphite furnace molecular absorption spectrometry (HR -MAS) for total fluorine determination in extractable organofluorines (EOF)

The determination of total fluorine content using high-resolution graphite furnace continuum source molecular absorption spectrometry (HR- MAS) has been employed in a variety of samples for over 10 years. However, most of the samples analysed by HR- MAS are rich in fluoride, with negligible levels of organic fluorinated species. With an increase in concern surrounding per- and polyfluoroalkyl substances (PFASs), new methods to measure total fluorine of organofluorine using different techniques have been developed. However, no studies focused on PFASs behaviour in HR-MAS have been performed. As these compounds encompass a wide range of different structures, boiling points, decomposition temperatures and matrix interactions, a loss of accuracy can occur when an aqueous external calibration is performed using only one compound. To overcome this issue, an investigation into permanent modifiers for the graphite furnace was performed. After optimisation similar sensitivity for different PFCA was achieved when 400 μg of W was used as a permanent modifier together with an optimised temperature program. The relative deviation between the different PFCA standard slopes relative to the PFOA slope was lower than 15%. The instrumental limit of detection and quantification (LOD and LOQ, respectively) of total fluorine as total PFCA was 0.1 mg L−1 and 0.3 mg L−1, respectively, while the method LOD and LOQ (using solid phase extraction) was 0.3 μg L−1 and 1.0 μg L−1, respectively. The developed method gave satisfactory recoveries for the spiked PFCA into seawater, river water and effluent using PFOA calibration standards. The optimised method is useful for measuring extractable organofluorines (EOF) when only ionic PFASs such as PFCA are expected. When other organofluorines are expected, the results using HR GF-MAS should be taken with caution.

Fluorine determination in biological and environmental samples with INAA using fast neutrons from a p(19 MeV) + Be neutron generator

We present a new activation method based on the 19F(n,2n)18F reaction using fast neutrons produced by a p(19 MeV) + Be accelerator-driven fast neutron source providing continuous neutron spectrum up to 17 MeV with a neutron fluence rate of approximately 9 × 1010 cm−2 s−1 at a 12-µA proton beam current. We describe elimination of interferences in measurement of 18F, a pure positron emitter with T1/2 = 1.83 h. We present results of fluorine determination for several biological and environmental reference materials with the new procedure and compare them with those achieved by other methods in terms of limits of detection, accuracy and precision, where available.

Indirect determination of chlorine and fluorine in eye shadow by ion chromatography after an eco-friendly sample preparation method based on combustion reaction

A powerful and efficient method for indirect determination of chlorine and fluorine in eye shadow is described in this work. The presence of these elements should be controlled in eye cosmetics because of its allergenic properties. The proposed method combines the analyte volatilization from eye shadow based on combustion reaction and the indirect determination of Cl and F by ion chromatography as chloride (Cl−) and fluoride (F−). To achieve better combustion conditions as well as to improve the volatilization of Cl and F from the sample matrix (which is mostly inorganic), microcrystalline cellulose was evaluated as a volatilization aid. The central composite rotatable design was used to optimize the sample mass and volatilization aid mass to be used in the microwave-induced combustion. Afterward, water or ammonium carbonate solutions (50, 100 or 150 mmol L−1) were evaluated for Cl and F absorption. Using the selected conditions (200 mg of eye shadow, 400 mg of microcrystalline cellulose, and water as absorbing solution) recoveries for Cl and F were 100 ± 8% and 106 ± 7%, respectively. Moreover, a mixture containing the certified reference material MESS-4 (marine sediment), microcrystalline cellulose and the sample was prepared by microwave-induced combustion, and no significant difference was observed between the result obtained for Cl (11,269 ± 325 mg kg−1) and the certified value (13,100 ± 4400 mg kg−1). The proposed method showed suitable trueness, precision (the repeatability and the intermediate precision was always lower than 7%) and limits of detection (LODs) for Cl (60 mg kg−1) and F (20 mg kg−1). Extraction of Cl and F from eye shadow assisted by ultrasound was also evaluated; however, the Cl and F recoveries were not quantitative and the LODs were considerably high. To the best of our knowledge, this is the first work demonstrating a reliable method for multielement determination in eye shadow, which is safe, presents low generation of laboratory effluents and may be considered an efficient approach for routine analysis in cosmetic industry.

CONTROL OF FLUORINE IN METALLURGICAL FUEL

Metallurgical fuel, including various types of mineral fuels: coke, hard coal, brown coal, peat, combustible shales and products of their technological conversion – needs environmental control of their use safety. When burning metallurgical fuel, harmful substances fall into the environment such as chlorine, fluorine, sulfur, arsenic, which worsen the environmental situation. Technical regulations on the safety of coal products contain requirements to limit the content of harmful impurities and their maximum permissible concentrations. Due to the wide spread of fluorine in natural and technological objects and the high toxicity of its compounds, the control of fluorine content is an urgent problem in the industrial use of metallurgical fuel. Physical methods for the determination of fluorine in solid fuel based on excitation of different spectra of the studies allow to identify it without decomposition directly in the source solid material, however, they have several limitations (sensitivity, accuracy of definition, complexity of hardware design). In other methods, mainly in ionchromatography and ionometry, samples are decomposed and fluorine is transferred into the solution. High temperature processes: pyrohydrolysis and combustion melting are usually used for decomposition. The aim of this work was to create a selective method for ionometric determination of fluorine with a fluoride-selective electrode. The study objects were samples of coal: brown, gas, semicoke, coke nut. Effective decomposition of the samples by two-stage high-temperature melting with KNaCO3 is proposed. Hydrolysis coprecipitation of accompanying interfering cations with chloride iron (II) was carried out for fluorine discharge in the solution in the form of free fluoride. The procedure of decomposition and ionometric determination of fluorine is described. The estimation of trueness and reproducibility of the developed technique by the method of sample variation was carried out. Fluorine content in the studied samples did not exceed the limit- tolerance values for commercial samples of coal products, which indicates the environmental safety of the samples in their subsequent energy application. The developed method is promising for the control of fluorine impurity in metallurgical fuel and is characterized by selectivity and simple carrying out.

Monitoring Fluorine in Metallurgical Fuel

The environmental impact of metallurgical fuel, which includes various types of mineral fuel (such as coke, coal, lignite, peat, fuel shales, and their derivatives) is a continuing concern. In the combustion of metallurgical fuel, harmful materials (chlorine, fluorine, sulfur, and arsenic) are released, with consequent environmental degradation. Safety regulations regarding coal production include restrictions on the content of harmful impurities and their limiting permissible concentrations. On account of the broad distribution of fluorine in nature and industry, it is of special importance to monitor the fluorine content in metallurgical fuel. Physical methods based on the excitation of various radiation spectra permit determination of the fluorine content, without decomposition of the initial solid sample. However, such methods have problems in terms of sensitivity, precision, and the complexity of the equipment required. In the ion-chromatographic, ionometric, and other methods, the samples are broken down, and the fluorine content is determined in solution. Usually, high-temperature processes are used for decomposition of the samples: pyrohydrolysis, combustion in oxygen and in a calorimetric bomb, and alkaline fusion. In the present work, a selective method is developed for the ionometric determination of fluorine, by means of a fluorine-selective electrode. Samples of lignite, gas coal, semicoke, and coke nuts are investigated. The samples may effectively be decomposed by two-stage high-temperature melting with KNCO3. Fluorine is transferred to solution in the form of free fluoride ions by means of hydrolytic codeposition of interfering cations with chloride iron(II). The analytical procedure is described. It consists of decomposition of the sample and the ionometric determination of fluorine. The precision and truness of the proposed method is verified by variation in the sample size. In the samples considered, the fluorine content is within the limits typical of commercial coal. That indicates that the use of the samples in fuel is environmentally acceptable. The proposed method is promising for the monitoring of fluorine impurity in metallurgical fuel. It is selective and simple to use.

Determination of Fluorine in Silicon Carbide Powder by Combustion Ion Chromatography

Determination of Fluorine in Silicon Carbide Powder by Combustion Ion Chromatography

Emission determination of fluorine using «Grand-Potok» complex with sample injection into dc arc by spill-injection method

An additional photodetector array BLPP-369 was installed on a «Grand-Potok» complex for rapid atomic-emission determination of the fluorine concentration in fluorite samples. Introduction of fluorite samples was carried out using the spill-injection method simultaneously with high pure calcium oxide introduction using the second conveyor belt. The use of an additional photodetector array with a spectral range of 528 – 536 nm provides the possibility of expanding the spectrum of CaF molecular lines with the intensity sufficient for determination of fluorine concentrations in fluorite samples. A calibration curve for fluorine determination in a concentration range of 0.12 – 47.63% was plotted using measurement results for 200 fluorite samples. Integration of the additional photodetector array provided increased detection limit for the mass fractions of fluorine up to the maximum possible concentrations in fluorite samples. The observed effect simplifies and speeds up the analysis in the absence of the necessity to dilute the sample, thus reducing the error of measurements. The results show that there is no need to introduce additional buffer mixtures (except CaO) and use reference lines to determine the fluorine concentration, which also simplifies the measurement procedure.

Total Fluorine Measurements in Food Packaging: How Do Current Methods Perform?

Per- and polyfluoroalkyl substances (PFASs) represent a class of more than 4000 compounds. Their large number and structural diversity pose a considerable challenge to analytical chemists. Measurement of total fluorine in environmental samples and consumer products is therefore critical for rapidly screening for PFASs and for assessing the fraction of unexplained fluorine(i.e., fluorine mass balance). Here we compare three emerging analytical techniques for total fluorine determination: combustion ion chromatography (CIC), particle-induced γ-ray emission spectroscopy (PIGE), and instrumental neutron activation analysis (INAA). Application of each method to a certified reference material (CRM), spiked filters, and representative food packaging samples revealed good accuracy and precision. INAA and PIGE had the advantage of being nondestructive, while CIC displayed the lowest detection limits. Inconsistencies between the methods arose due to the high aluminum content in the CRM, which precluded its analysis...

Feasibility of pyrohydrolysis as a clean method for further fluorine determination by ISE and IC in high purity nuclear grade alumina

In this work, a method based on pyrohydrolysis of high purity nuclear grade alumina and subsequent F determination by ion chromatography (IC) and ion selective electrode (ISE) was developed. After pyrohydrolysis, F was absorbed in a suitable solution (50 mmol L−1 (NH4)2CO3, 50 mmol L−1 NH4OH, and also water were evaluated). Using the selected conditions, it was possible to digest a high sample mass (500 mg) in only 10 min. The following analytical parameters were evaluated: pyrohydrolysis temperature (550 to 1050 °C), time of reaction (2.5 to 20 min), air flow-rate (0.1 to 0.4 L min−1), water flow-rate (0.1 to 1.0 mL min−1), and the use of V2O5 (200 mg), as an auxiliary reagent. Quantitative F recoveries were obtained using air and water flow-rates pumped through the reactor at 0.2 L min-1 and 0.5 mL min−1, respectively. Only water was required as absorbing solution and the use of V2O5, generally recommended for inorganic matrices, was not necessary. Detection limits of 2.0 and 3.6 μg g−1 using IC and ISE, respectively, were obtained. Accuracy was evaluated by recovery tests and also by comparison with the results obtained by high resolution continuum source graphite furnace molecular absorption spectrometry (HR-CS GF MAS). Suitable recoveries for F were obtained (95%) and no statistical difference (95% of confidence level) was observed for the results obtained by HR-CS GF MAS. Pyrohydrolysis allowed the F volatilization in a relatively short time avoiding the use of concentrated reagents and making possible further determination by both analytical techniques (IC or ISE). The pyrohydrolysis method was considered suitable for further F determination, avoiding excessive dilution of digests or matrix matching approaches, making this method a suitable option for routine F determination in nuclear grade alumina samples.

Chlorine and Fluorine Determination in Eye-Pencil: Development of an Eco‑Friendly Sample Preparation Method for Ion Chromatography Analysis

In this paper, a feasible method was proposed for the chlorine and fluorine determination in eye-pencil samples using ion chromatography (IC). The microwave-induced combustion (MIC) was used to digest up to 200 mg of a sample, with 50 mg of microcrystalline cellulose as a combustion aid and only water for analytes absorption. Cl and F recoveries were 105 ± 1 and 93 ± 5%, respectively, when standard solutions were used in the recovery tests. Certified reference materials (CRM) were also digested mixed to the sample, and no significant difference between the obtained results and the certified values was observed. Precision was assessed in terms of repeatability and intermediate precision, with relative standard deviations (RSD) lower than 9%. Limits of detection (LOD) for Cl and F were 37 and 4 mg kg-1, respectively. Ultrasound-assisted extraction (UEA) was also evaluated; however, the results were not satisfactory. The proposed method was suitable for Cl and F determination in eye-pencil because it proved to be accurate, precise and safe, and also minimized waste generation and had high throughput.

Влияние функциональных групп поверхности углеродных материалов на эффективность очистки экстракционной фосфорной кислоты от соединений фтора

The environmental problems of the production of extraction phosphoric acid and the effect of fluorine on the human body are discussed in the article. The creation of the industry of phosphoric fertilizers on the basis of processing of fluorine-containing phosphate raw materials and fluorine-containing compounds, the development of their application require the study of environmental consequences arising from this, because fluorine is characterized by high mobility in the biological cycle of metabolism. For the purification of phosphoric acid from fluorine was used carbon adsorbents such as active charcoal brand BAU, natural graphite deposits Kyshtymsky, P514 soot, charcoal. Experiments on the purification was carried out on non-evaporated half-hydrated extraction phosphoric acid which was produced by joint stock company «Apatit» in Cherepovets city in Russia. The following analyses were carried out: IR-Fourier spectrometry, research of acid–base properties of carbon materials by potentiometric titration, potentiometric method of fluorine determination in extraction phosphoric acid. It is mentioned that the carbon black P514 is the most efficient adsorbent for purification of extraction phosphoric acid. The total number of functional groups on its surface is 0.62 mmol/g, the degree of purification from fluorine compounds is 94.8%.

Novel non-targeted analysis of perfluorinated compounds using fluorine-specific detection regardless of their ionisability (HPLC-ICPMS/MS-ESI-MS)

Although perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) have been phased out, there is a plethora of per- or polyfluoroalkyl substances (PFAS) generated and only a small number of these compounds are currently being monitored in environmental and biological sample using molecular mass spectrometry (MS). Total fluorine determination has revealed that a substantial amount of fluorinated organic compounds has not been identified. Due to the small mass deficiency of fluorine, it is not an easy task to screen successfully all fluorinated compounds including those which are not easy ionisable, hence a novel fluorine-specific detector is needed. Here, inductively-coupled plasma mass spectrometry (ICPMS) was used for the first time for the detection of PFAS, by using the novel approach to transfer F− into a detectable [BaF]+ in the argon plasma. A reverse phase-high performance liquid chromatography (RP-HPLC) method was developed and then online coupled to ICPMS/MS for the fluorine-specific detection and simultaneously to electrospray MS (ESI-MS) to separate perfluorinated carboxylic acids (PFCA) and perfluorooctanesulfonic acid (PFOS). The calibration was linear and was element-specific with detection limits of 0.49 mg F L−1 under gradient elution method. As a proof of concept, PFCA standards in methanol were not fully neutralised to force the esterification and those solutions were measured using HPLC-ICPMS/MS-ESI-MS. The methyl esters were not detectable by ESI-MS but by ICPMS/MS. This illustrates that the undetectable fluorine-containing compounds were detected and quantified by the element-specific detection of ICPMS/MS. The analysis of spiked river water at sub-ppb level gave an acceptable recovery using a SPE-based preconcentration method. Since ICPMS/MS method is an element-specific detection, all non-fluorinated compounds interfering in ESI-MS were eliminated. Hence, HPLC-ICPMS/MS can be used as a non-targeted method of fluorinated compounds which helps the identification of novel fluorinated compounds in environmental and biological samples and helps with mining the ESI-MS data.