Determination Of Fluorine Research Articles

Simultaneous determination of chlorides, bromides, and fluorides in ion-conducting electrolyte

There are developed the techniques of determining the content of chlorides, bromides and fluorides at their joint presence in two types of solid electrolytes differing in matrix content: the first type contains lithium, the second one — both lithium and aluminium, simultaneously. Determination of bromides mass fraction is fulfilled using a method of iodometric titration of iodic potassium excess after bromides are oxidized until free bromine. The fluorides mass fraction is measured by the gravimetric method in the form of fluoro-chloride of lead, in this case the aluminium interfering influence is eliminated by its precipitation in the form of hydroxide after it is fused with carbonates of potassium and natrium, as well as by the method of potentiometric titration with a fluoride ion-selective electrode using the nitrate lanthanum solution. The absence of aluminium interfering influence on the result of fluorine determination is estimated by the «input – found» method. The mass fraction of chlorides is determined by calculation by difference between results of determining the sum of chlorides and bromides using the method of mercurometric titration and — separately — the bromides mass fraction. Optimal conditions of samples preparation and analysis for each of mentioned methods of analysis were selected. The limits of the relative total error of determining bromides in the range of mass fractions from 28.0 to 41.0% is ±2.1%, chlorides within the mass fraction range from 8.0 to 15.0% — ±3.6%, fluorides within the mass fraction range from 3.0 to 7.0% — ±3.4% using gravimetric method and within the mass fraction range from 5.0 to 8.0% — ±1.5% using a method of potentiometric titration. The developed techniques were certified by a metrological service of the enterprise and are used to control the chemical composition of the ion-conducting electrolyte. The techniques do not require expensive equipment, and can be used in factory laboratories.

Determination of fluorine in reference materials by chopped-beam cold neutron prompt gamma-ray activation analysis (CB-CNPGAA)

AbstractA method is described for determination of fluorine in reference materials by chopped beam cold neutron prompt gamma-ray activation analysis (CB-CNPGAA). The chopper cycle is set to 11 s on/off to match the t1/2 of 20F. To reduce systematic error, the F mass is measured as the ratio to a comparator element, either Ca or Cl. The F mass fraction is then calculated by multiplying this ratio by the mass fraction of the comparator element. The method is used to measure F in SRMs 1486 Bone Meal, 1400 Bone Ash, 1566a Oyster Tissue, and 2695 Fluorine in Vegetation.

Determination of Chlorine and Fluorine in Teas by Ion Chromatography after Pyrohydrolysis Sample Preparation Optimized by Box-Behnken Design

Determination of Chlorine and Fluorine in Teas by Ion Chromatography after Pyrohydrolysis Sample Preparation Optimized by Box-Behnken Design

Method development for multielement determination of halogens and sulfur in teas

Abstract Microwave-induced combustion was evaluated as a sample preparation method for several types of tea (black, green, lemon balm, boldo, and mint) for further determination of bromine, chlorine, fluorine, iodine, and sulfur by ion chromatography. Parameters such as the sample mass efficiently decomposed and the most suitable absorbing solution (ultrapure water and 25, 50, 100, and 150 mmol L−1 NH4OH) were evaluated, considering the characteristics of the analytes and the determination technique used. The maximum sample mass possible to be decomposed was 900 mg of milled tea in the form of pellets, and the absorbing solution chosen was 100 mmol L−1 NH4OH, which provided suitable stabilization of the analytes (recoveries between 95 % and 103 %). To assess the accuracy of the proposed method, a certified reference material (BCR 060, aquatic plant) was analyzed. Agreements with the certified values ranged from 101 % to 107 %. The proposed method was used to analyze tea samples and the concentrations ranged from 549 to 2,549 mg kg−1 for chlorine, 223 to 828 mg kg−1 for fluorine, and 786 to 4,023 mg kg−1 for sulfur; bromine and iodine concentrations were below the limits of quantification (42 and 80 mg kg−1, respectively) in all evaluated samples.

Determination of Fluorine by Ion-Selective Electrode and High-Resolution Continuum Source Graphite Furnace Molecular Absorption Spectrometry with Respect to Animal Feed Safety.

Fluorine, depending on its concentration and chemical form, is essential or toxic to humans and animals. Therefore, it is crucial to be able to determine it reliably. In this study, fluorine was determined in animal feed after extraction with HCl (gastric juice simulation). The standard potentiometric method with a fluoride-selective electrode (ISE) and newly developed high-resolution continuum source graphite furnace molecular absorption spectrometry (HR-CS GFMAS) method was applied. Feed samples turned out to be a challenge for HR-CS GFMAS. Chemical interferences (formation of competing molecules, CaF, GaCl, and GaP, instead of the target GaF molecule) and spectral effects (including a phosphorous molecule spectrum and atomic lines) were identified. An additional difficulty was caused by reagent contamination with F and memory effects. Difficulties were eliminated/reduced. The quality of ISE analysis was multi-directionally verified (including comprehensive proficiency testing). A risk of inaccuracy at low F concentration, where the calibration relationship is nonlinear, was investigated. The results of both methods were consistent, which confirms the accuracy of the methods and informs that the extracted fluorine is in fluoride form. The results of extensive ISE tests conducted in Poland in 2021-2023 have shown that, in most cases, the fluoride content is significantly lower than the threshold values.

Determination of organic fluorinated compounds content in complex samples through combustion ion chromatography methods: a way to define a “Total Per- and Polyfluoroalkyl Substances (PFAS)” parameter?

Emerging contaminants are a growing concern for scientists and public authorities. The group of per-polyfluoroalkyl substances (PFAS), known as ‘forever chemicals', in complex environmental liquid and solid matrices was analysed in this study. The development of global analytical methods based on combustion ion chromatography (CIC) is expected to provide accurate picture of the overall PFAS contamination level via the determination of extractable organic fluorine (EOF) and adsorbable organic fluorine (AOF). The obtained results may be put into perspective with other methods such as targeted analyses (LC-MS/MS). The impact of pH, the presence of dissolved organic carbon and suspended particles on AOF measurements were explored. The effectiveness of the washing step to remove adsorbed inorganic fluorine (IF) has been proven for samples containing up to 8 mgF.L−1. CIC-based methods showed good repeatability and reproducibility for the complex matrices studied. Environmental applications of these methods have been tested. AOF and EOF analyses could explain between 1 % and 23 % and 0.1 % to 2 % of total organic fluorine (TOF), respectively. The sum of PFAS compounds expressed as fluorine could explain from 0.2 % to 11 % and from 0.003 % to 5 % for AOF and EOF, respectively. These results also suggest that some fluorinated compounds are not adsorbed or extractable and/or lost by volatilisation during the application of AOF and EOF analytical procedure. These findings highlight that AOF and EOF are not entirely efficient as proxy to assess “total PFAS” for assessing environmental contamination by PFAS. However, these methods could still be applied to gain a better understanding of the sources and fate of PFAS in the environment.

Second-order calibration high-resolution continuum source graphite furnace molecular absorption spectrometry-based determination of bromine and fluorine

In this study, we report the simultaneous determination of bromine and fluorine using Second-Order Calibration High-Resolution Continuum Source Graphite Furnace Molecular Absorption Spectrometry (HR CS MAS). The instrumental data acquired correspond to the time versus wavelength matrix per sample that were analyzed using Parallel Factor Analysis (PARAFAC), along with Unfold and N-way Partial Least Squares combined with a post-calibration step known as Residual Bilinearization (U and N PLS/RBL). Despite the significant difference in sensitivity between bromine and fluorine, all approaches provided reasonably accurate results when predicting both analytes in synthetic mixtures within a controlled environment. The relative prediction error (REP) values for bromine were 29.8 % (PARAFAC), 23.6 % (N-PLS/RBL), and 13.1 % (U-PLS/RBL), while for fluorine, the REP values were 3.4 % (PARAFAC), 3.5 % (N-PLS/RBL), and 3.2 % (U-PLS/RBL). When applying this approach to predict unknown samples, a comparison was made between the estimated nominal concentrations of fluorine and bromine obtained using either a reference method or based on labeled values or spiked mass, and those obtained using the proposed method. It was observed that PARAFAC was unable to predict the samples accurately, whereas the REP values for the prediction of bromine and fluorine using N-PLS/RBL and U-PLS/RBL methods were 19.3 %/19.2 % and 13.6 %/13.1 %, respectively.

A simple, low cost and fast sample preparation method for fluorine determination by ISE in leguminous seeds and oilseeds.

This work presents the first report of the application of microwave-induced combustion in disposable vessels (MIC-DV) as a simple and fast sample preparation step for fluoride determination by ion-selective electrode (ISE) in leguminous seeds and oilseeds samples. Several experimental conditions of MIC-DV were evaluated, such as sample mass, absorbing solution, volume of combustion igniter, purging time with oxygen, and the use of successive combustion cycles. The accuracy of MIC-DV/ISE method was evaluated by comparing the results obtained by microwave-induced combustion and determination by ion chromatography, with agreements ranged from 94 to 106%. The method allowed to achieve relatively low limits of quantification (8.3 to 16µgg-1) comparing to AOAC method (40µgg-1), besides the use of small amounts of reagents, less handling of digests, making the method greener and with portable features comparing to other methods.

Strontium monofluoride – a new molecule to measure fluorine using high-resolution continuum source flame molecular absorption spectrometry and its application for gasoline analysis

In this work, for the first time, strontium monofluoride was generated in an air-acetylene flame of a high-resolution continuum source molecular absorption spectrometer with the aim of fluorine determination via molecular absorption. The particular task was the determination of organic fluorine in gasoline/its components dissolved in xylene. Sequential measurements in the area of the most intensive absorption of the molecule were executed to select the spectral range for analysis. The acquired spectra differed from the ones from the literature, especially the emission spectra. The best and comparable sensitivity has been registered near 651 nm and 663 nm in measurements of rotations from the range of the X2Σ+ → A2Π electronic transition of the SrF molecule. Unfortunately, SrOH molecules were also spontaneously formed and absorbed radiation in the selected area. No other spectral interferences were found, except absorption by the SrBr molecule, which could have been formed in the flame despite a relatively low energy bond of 330 kJ/mol. The dependence of generation of the SrF and the SrOH molecules on the flame conditions was studied for pure solvent (xylene) and solutions of investigated samples of gasoline type. The effect of the SrOH molecule was overcome by blank subtraction or the least square background correction. The last method had to be used to overcome the SrBr effect. Due to the various combustion properties of various hydrocarbons and their different behaviour in flame, applying the simplified standard addition method became indispensable. As a source of strontium, an oil Sr standards or Sr acetylacetonate (SrAA) were investigated. The crucial benefit of SrF molecule application was the relatively good solubility (and relatively low price) of SrAA. Under the selected conditions, the characteristic concentration of fluorine was 1.9 and 2.0 mg/L, while the instrumental detection limit was 0.5 and 0.8 mg/L for the 651 and 663 nm ranges, respectively. The analytical technique enables the analysis of samples diluted to a small degree, e.g. 1:3 v:v and the best method detection limit is 1.3 mg/L. The proposed method is fast and cheap.

Experience of the Determination of Fluorine in Rocks by X-Ray Fluorescence Spectrometry

The main fluorine-concentrating minerals in rocks are mainly apatites, amphiboles, micas, fluorites, sphenes, villiomites, in which fluorine is found in compounds with Ca, Mg, Na. The yield of the X‑ray fluorescence of fluorine depends on the element with which it is chemically bound. Taking into account this factor, three versions of calibration dependences for fluorine in the composition of CaF2, MgF2, and NaF were obtained using pressed tablets. Mixtures of these fluorides with granite, basalt, and limestone were used for calibration. To select an adequate calibration for the determination of fluorine in a batch of unknown samples, it was proposed to use the results of a selective analysis of fused samples of the batch

Experience of the Determination of Fluorine in Rocks by X-Ray Fluorescence Spectrometry

Experience of the Determination of Fluorine in Rocks by X-Ray Fluorescence Spectrometry

Corrigendum to Determination of fluorine and chlorine in standard steel residues and zinc sulfide concentrates by ion chromatography-matrix interference study: [Chinese Journal of Analytical Chemistry 51 (2023) 1–8/100147

Corrigendum to Determination of fluorine and chlorine in standard steel residues and zinc sulfide concentrates by ion chromatography-matrix interference study: [Chinese Journal of Analytical Chemistry 51 (2023) 1–8/100147

Determination of fluorine and chlorine in standard steel residues and zinc sulfide concentrates by ion chromatography-matrix interference study

1 Ion chromatographic based determination of F − and Cl − . 2 Investigation of the effect of matrix constituent elements on F − and Cl − recovery. 3 Digestion of steel residues and zinc sulfide concentrate standard samples. 4 Various parameters of alkali fusion were optimized. The sensitive determination of trace fluorine and chlorine contents in complex inorganic matrices such as steal residues and zinc sulfide concentrates is challenging cause difficulty in their digestion and presence of various matrix interferences species. Therefore, in this study, the effect of various constituent elements of geological samples including Ni, As, Ag, Pb, Hg, Co, SiO 2 , Bi, Sb, Cr, Zn, Cd, Ag, CaO, MgO, Al, Fe, KBr, and KI on the alkali-fused steam distillation-based recoveries of fluoride and chloride were investigated for better understanding the application of this method in various geological samples. Hence, a simple, cost-effective and modified alkali fusion-steam distillation-ion chromatography (SD-IC) method was developed for the sensitive and selective determination of halogens in standard steel resides and zinc sulfide concentrate samples. For optimum extraction of analytes various digestion parameters including alkali fusion amount, fusion temperature, and fusion time along with distillation volume were sequentially optimized. The developed method shows good linearity in the range 0.2 - 3.0 mg/kg with correlation coefficient (r) values greater than 0. 99991. The limit of detection for fluoride and chloride were appeared 0.07326 mg/kg and 0.02331 mg/kg, respectively with precision (repeatability and the intermediate precision) less than 4.12%. The results of standard steal residue and zinc sulfide concentrate samples were in good agreement (91.27- 100.18%) with their certified reference values (CRMs). SD-IC is a simple, cost-effective, and sensitive method for the determination of fluoride and chloride contents in complex geological samples (steal residues and zinc sulfide concentrates).

Ion Selective Electrode (ISE) Method for Determination of Total Fluorine and Total Organic Fluorine in Packaging Substrates

Various testing methods and techniques have been used to identify and quantify per- and polyfluoroalkyl substances (PFAS) in food packaging. A common indirect measurement of PFAS is total fluorine (TF) and total organic fluorine (TOF). These methods are critical in rapidly screening food packaging materials for the >9000 PFAS and are often globally used for regulatory limits. However, this destructive approach requires careful sample preparation, combustion, and the analysis of the solution by a fluoride-specific electrode. The method described herein is a cost-effective, rapid, quantitative, and externally validated initial screening of packaging materials for fluoro-chemistry. This study presents validated protocols for measuring TF and TOF in packaging substrates using oxygen combustion sample preparation coupled with fluoride ion-selective electrode (F-ISE); the materials and required equipment are provided, and the step-by-step procedure from sample preparation to the analysis are described, including critical steps to minimize contamination and interferences during sample preparation.

Nebulization assisted molecular LIBS for sensitive and fast fluorine determination in aqueous solutions

In this work, an analytical methodology based on nebulization-assisted laser-induced breakdown spectroscopy for the analysis of fluorine in aqueous solutions via CaF molecular emission was developed and successfully tested with real mouthwash samples.

Direct Quantitative Analysis of Fluorine in Solid Samples by Cryogenic Laser Ablation and Ionization Time-of-Flight Mass Spectrometry.

The determination of fluorine, the lightest element in halogens, suffers from high ionization potential and spectral interference from water molecules in mass spectrometry. Herein, we introduced a liquid nitrogen cooling unit into the laser ablation and ionization source for the first time to construct a cryogenic laser ablation and ionization time-of-flight mass spectrometry (Cryo-LAI-TOFMS) system. With this system, the interference of water-related species at m/z 19 was effectively eliminated, and fluorine atomization and ionization efficiency could reach 6.3%. A direct quantitative analysis method was developed to determine fluorine contents in phosphate rock, copper ore, industrial byproduct gypsum, stream sediment, and soil. Considering the simplicity, high sensitivity, and low spectral interference of this technique, it can be extended to the determination of fluorine content as low as μg/g in complex solid samples.

Separation and determination of boron, chlorine, fluorine and molybdenum in uranium silicide using pyrohydrolysis and ion chromatography

Separation and determination of boron, chlorine, fluorine and molybdenum in uranium silicide using pyrohydrolysis and ion chromatography

Direct emission spectrometry determination of fluorine in carbon materials: Argon dc arc and spark radiation sources

In this work, the procedure for direct atomic emission spectrometry (AES) determination of fluorine impurities in carbon materials was proposed. Two types of simple radiation sources with direct solid (powdered) sample introduction were studied: direct current arc (25A) and high-power low voltage spark (300 V, of 2348 μF). For each source, standard graphite extra high purity electrodes and argon discharge atmosphere were used. Red spectral region approach to non-metal AES determination was employed with analytical line F I 685.603 nm. The spectra were registered by compact tunable fiber-optic spectrometer with linear complementary metal oxide semiconductor array (CMOS) sensor and short-focus lens. Special measures were taken to counter red spectral region interferences, such as CN molecular bands and thermal radiation. The excitation of F in both types of radiation source was studied. A set of artificial graphite and NaF based standards was prepared for calibration and evaluated by two independent approaches: indirect dc arc AES and water extraction photometry. Limit of detection was determined for dc arc source was 5 μg/g, and for spark 20 μg/g of F. The whole cycle of measurement with each type of radiation source takes 10 min. As the power of dc arc is limited by generator capabilities, it is possible that even lower limit of detection is achievable with higher discharge current.

Characterization of toothpastes for fluorine and other elements by INAA and ICP-OES

Abstract Fluoride toothpastes have made a significant contribution towards oral hygiene. This study proposes instrumental neutron activation analysis (INAA) as a suitable technique for determining fluorine in toothpastes. The method involved a 10 s irradiation, followed by 10–20 s decay, and counting for 10 s, using a pneumatic system and high purity germanium detector. All irradiations were performed at miniature neutron source reactor with thermal neutron flux 1 × 1012 cm−2 s−1. Since Na was present in all toothpastes, the quantification of fluorine required correction for 23Na(n,α)20F threshold reaction. Fluorine determination was validated by analysing the samples by ion chromatography. All toothpastes were also analysed for other elements by k 0-INAA and ICP-OES. Both techniques quantified 28 elements including Al, As, Ba, Ca, Ce, Cl, Co, Cr, Cu, F, Fe, Hf, K, La, Mg, Mn, Na, P, S, Sb, Sc, Si, Sm, Sn, Sr, Ta, Ti and Zn. This study, categorized toothpastes in five groups based on concentrations of Ca, P and Ti.

Combining microwave and ultraviolet energy for sample preparation of polymer-based materials for further halogen determination

In this work, a microwave-assisted ultraviolet wet digestion (MAWD-UV) protocol was used to digest polymer-based materials (e-waste, food packing, medical-care materials, and individual protection equipment) for further halogen determination. Digests were suitable for Cl, Br, and I determination by inductively coupled plasma mass spectrometry (ICP-MS) or inductively coupled plasma optical emission spectrometry (ICP-OES). Fluorine determination was performed with ion selective electrode (ISE). The power radiation and the digestion solution were evaluated. The accuracy was evaluated by comparing the results with those obtained after neutron activation analysis (NAA) for Cl and Br or using microwave-induced combustion (MIC) as sample preparation for F and I. Two certified reference materials (CRM) of low-density polyethylene (ERM EC680k and EC681k) were evaluated, and no differences were observed (t-test, 95% confidence level) between the results and the certified values. Quantitative recoveries for Cl, Br, and I were obtained using 200 mg of the sample using diluted acid solution (15 mL of 0.5 mol L−1 HNO3 plus 10.6 mol L−1 of H2O2), with a 40 min radiation program (700 W, 25 min ramp). No statistical differences (ANOVA, 95% confidence level) were observed between the MAWD-UV and ICP-MS results and the reference values for Cl, Br, and I for several samples. However, results were lower than the reference values for fluorine, indicating that digestion efficiency was poor for this analyte, which was probably as an organic molecule (likely polytetrafluoroethylene). The limit of quantification (LOQ) was 0.216 mg g−1 for Cl, 3.33 µg g−1 for Br, and 0.036 µg g−1 for I using ICP-MS. The main advantage of MAWD-UV is that it enables decomposing several polymer-based matrices using diluted acid without halogen losses. The developed method represents an important contribution to the digestion of these hard-to-digest matrices and in compliance with green analytical chemistry, thereby being an advance in sample preparation.