Determination Of Fluoride Ion Research Articles

Solvent extraction and fluorometric determination of fluoride ion at ppb level in the presence of large excess of aluminum(III) and iron(III) by using an expanded porphyrin, sapphyrin

Solvent extraction of fluoride as low as 10 −6 M into chloroform using [2,23-diethyl-8,17-bis(2-ethoxycarbonylethyl)-3,7,12,13,18,22-hexamethylsapphyrin (H 3sap), sapphyrin] have been studied in the presence of 0.1 M sodium nitrate by spectrophotometric and fluorometric methods at pH 3–13 and 25°C. Sapphyrin is protonated at pH<8 and exists as the ion-pair complexes with nitrate ion, such as H 4sap +·NO 3 − and H 5sap 2+·2NO 3 − in chloroform. The equilibrium constants, K 1 for [H 4sap +·NO 3 −] org[H 3sap] org −1[H +] aq −1[NO 3 −] aq −1 and K 2 for [H 5sap 2+·2NO 3 −] org[H 4sap +·NO 3 −] org −1[H +] aq −1[NO 3 −] aq −1 were found to be 9.90±0.08 and 7.20±0.07 in the logarithmic form, where the subscripts of org and aq denote the chemical species in organic and aqueous phases, respectively. Fluoride ion was extracted from chloroform with the positively charged sapphyrin that gave a new absorption maximum wavelength at 448 nm. The extraction constant, log ( K FP), for the reaction of (F −) aq+(H 5sap 2+·2NO 3 −) org⇌(H 5sap 2+·F −·NO 3 −) org+(NO 3 −) aq was 3.66±0.01. These results were applied to the determination of fluoride in natural waters containing Al(III) and Fe(III) by the measurement of fluorescence intensity at 684 nm under excitation at 448 nm. Al(III) of 10 −4 M and Fe(III) of 10 −3 M were quantitatively masked by DCTA ( trans-1,2-aminocyclohexane- N, N, N′, N′-tetraacetic acid).

Determination of fluoride ion in aqueous samples by inductively coupled plasma atomic emission spectrometry with tungsten boat furnace vaporiser

A procedure for the determination of fluoride ion in aqueous solution was investigated. By using a tungsten boat furnace (TBF) vaporiser system, a micro-volume of aqueous sample solution was converted into atomic and/or molecular vapour, and the resulting vapour was transported to the plasma. By placing a small amount of tetramethylammonium hydroxide solution in the TBF as chemical modifier prior to analysis, the loss of fluorine, which would occur during the drying stage, was suppressed. With this system, the detection limit (3σ) of 6.39 µg of the aqueous fluoride ion was achieved. The relative standard deviation for ten replicate determinations was 5.0% for 100 µg of the fluoride ion. The calibration graph was linear in the tested range of up to 200 µg of the fluoride ion. Analytical results of several leachings out of rubber samples made of fluorocarbon polymer are given.

Gradient flow titration for the determination of fluoride ion in natural waters

The determination of fluoride ions in water samples was accomplished by using a gradient flow titration. A standard commercial combined electrode is used in a cell configuration that combines the gradient chamber and the electrode in a single unit. The methodology developed gives results with a relative standard deviation of about 3%. The average recoveries after spiking natural samples with fluoride are in the range 100–102%. The method was used successful in determining the fluoride concentration in water samples.

Spectrophotometric and complexometric methods for the determination of thorium and fluoride using bromocresol orange reagent

The ternary purple coloured complex formed between Th 4+, bromocresol orange (BCO) and cetylpyridinium bromide (CPB) in acidic medium was investigated spectrophotometrically. Results obtained revealed the formation of 1:1:1, Th:BCO:CPB complex in aqueous solution at pH≈0.5 with a logarithmic conditional stability constant of 12.04±0.1, I=0.1 at 25°C. The colour of the ternary complex was used for the determination of thorium(IV) in the range of 0.02–2.6 μg ml −1 Th 4+, ϵ=9.2×10 4 l mol −1 cm −1 at 560 nm. Beside its high sensitivity, the reaction was also proved to be highly selective for Th 4+. Thorium(IV) was determined in presence of great number of transition metal ions, rare earths and different anions. Th 4+ was also determined with high accuracy and precision by its titration with disodium ethylenediaminetetraacetate (Na 2EDTA) using BCO as an indicator at pH≈0.5. The endpoint was detected either visually or spectrophotometrically ( λ=550 nm). The proposed procedures were successfully applied for the determination of Th 4+ in standard Th-U ores and in a series of naturally occurring ores or minerals containing thorium. A spectrophotometric method was also described for the determination of fluoride ion, which was based upon the decrease in colour intensity of the Th-BCO complex on mixing it with F − ion. The proposed method was convenient, rapid and sensitive for fluoride. It could be used for the determination of fluoride ion in the 0.02–3.00 μg ml −1 range (S.D.±0.9%). The proposed method was successfully applied for direct determination of F − ion in water obtained from different origins and the results were satisfactory.

Fluoride release from glass-ionomer and compomer restorative materials: 6-month data

Objectives: To investigate the daily fluoride release of two glass ionomers (Ketac-Fil and ChemFil Superior) and two compomers (Compoglass and Dyract Restorative) over 6 months. Methods: A pilot study evaluated the time taken for sample solutions to equilibrate to establish an appropriate time period for sample solution storage between fluoride ion measurements. In the main study storage water replacement and fluoride ion determination was made daily using a specific ion electrode, TISAB buffer and standard solutions for calibration. Results: Equilibration of fluoride concentration in aqueous solution occurred in under 48 h for all materials. Total fluoride released (μg mm − 2) after 6 months by Ketac-Fil (30.6, s.d. 4.9) was significantly greater than ChemFil Superior (12.7, s.d. 2.5), Compoglass (10.4, s.d. 1.0) and Dyract Restorative (7.7, s.d. 1.7) ( P < 0.05). Daily fluoride release at 24 h and 10 days was significantly higher for the glass ionomers than the compomers ( P < 0.05). After 40 days the daily fluoride release (μg mm − 2) from ChemFil Superior (0.05, s.d. 0.01) was not significantly different from Compoglass (0.04. s.d. 0.01) and Dyract Restorative (0.03, s.d. 0.00) ( P > 0.05). Daily fluoride release from Ketac-Fil remains significantly higher than the compomers at 3 and 6 months ( P < 0.05). Conclusions: Specimens stored in water equilibrate rapidly, suggesting the rate at which storage water is changed may alter the relative fluoride release rates of materials. This important fact is often overlooked. Fluoride release from the glass ionomers is initially higher than for the compomers. Fluoride release from glass ionomers falls rapidly to approach levels released by compomers. Compomers produce no initial burst of fluoride and levels of release remain relatively constant.

Aluminum ions in analysis of released fluoride from glass ionomers

Objectives: Aluminum ions interfere with fluoride determination when an ion-selective electrode (ISE) method is used. This study examined the effect of the presence of aluminum ions on the determination of fluoride ions released from glass ionomers. Methods: Disk-shaped specimens of five different commercial glass ionomers were immersed in deionized distilled water at 37 °C for one day or up to seven weeks. The amounts of released aluminum were determined by atomic absorption spectrophotometry, whereas the released fluoride was quantitated using a fluoride ISE with TISAB plus two different decomplexing agents for aluminum (CDTA or sodium citrate-potassium nitrate) or TISAB only. Results: Released amounts of aluminum and fluoride ions were found to be significantly different among the five different glass ionomers tested. Based on preliminary examination of the effect of the amount of aluminum ions on the measured value of fluoride, it was found at the end of one day for some of the glass ionomers that the fluoride concentrations measured without decomplexing agents were significantly lower than those measured with decomplexing agents, depending on the amounts of aluminum in the solution. However, since all the glass ionomers tested leached out most of the aluminum ions by seven days, the measured fluoride concentrations were not affected by a small amount of released aluminum from the glass ionomers immersed longer than seven days. Conclusions: When fluoride release from the glass ionomer is determined using ISE, care must be taken with the experimental design and analytical procedures to eliminate the interference by aluminum ions.

Spectrophotometric determination of fluoride in dosage forms and dental preparations

The method is based upon the reaction between fluoride ions and the coloured complex of Fe(III) with methyl salicylate to form the stable, colourless hexaflouride complex of iron. The conditions of the method (pH, time and combination ratio) were studied and a standard curve was obtained for 0.01–0.08 mg NaF ml −1, at 525 nm. A study was conducted on interference with complexing anions of Fe(III), cations that react with fluoride ions and with common ingredients of dosage forms and dental preparations. The method was validated and the results showed good precision (100.16 ± 2.33%) comparable with that of other analytical methods. Good results were obtained in the spectrophotometric determination of fluoride ions in a stomatological gel and in a toothpaste.

Are They Really Sloppy?: A Comparative Analysis of Student Performance in the Laboratory

The performance of the students in the analytical laboratory was tested in a potentiometric determination of fluoride ion in anti-caries dental tablets. The analytical results determined by freshman students and experienced personnel were compared. The error in the student's experiments was only about two times bigger than in the reference determinations. The lack of experience mainly affected students in complex tasks.

Elimination of Metal Interference in the Determination of Fluoride Ion by Non-Suppressor Type Ion Chromatography

Abstract A simple method has been developed to eliminate metal interferences in the ion-chromatographic determination of fluoride ion in aqueous solutions. Negative interferences become appreciable on 0.2-mM F− at 0.01 to 0.02 mM of Al(III), Ce(IV), La(III), Y(III), Ce(III) and Pb(II); and at 0.25 mM of Ca(II). The interference from Cd(II), Co(II), Fe(II) and Ni(II) is insignificant at ≤ 5.0-mM metal for 5.0-mM F−. By alkalifying F− solutions at pH 12.3, the metal interference can be eliminated up to the concentrations of 0.25-mM Al(III), La(III) and Y(III); 1.0-mM Ce(IV); 2.5-mM Ce(III); and 5.0-mM Pb(II), Cd(II), Co(II), Fe(II) and Ni(II). The Ca(II) interference cannot be eliminated. The pretreatment enables determination of 0.2- to 5.0-mM F− in presence of 0.25-mM Al(III) or La(III) with coefficient-of-variations of 1.99 to 6.20%.

Evaluation of a Complexation Solid-Phase Extraction Method for Eliminating Interferences Caused by Metal Ions in the Determination of Fluoride Ion in Water.

Although ion chromatography is known as a good separation method for inorganic ions, some interference arises from co-eluting substances, such as borate, silicate, formate and acetate, in the determination of fluoride ion . For eliminating these interferences, postcolumn derivatization methods with lanthanum-ALC (Alizarin complexone), 8-hydroxyquinoline sulfonate and Xylenol Orange have been reported.

Automated gravimetric management of solutions. Part 2. Automated gravimetric approach to direct potentiometry and kappa number determination

The high-performance microcomputer controlled gravimetric burette described in Part 1 has been employed to automate some routine analytical procedures. A direct potentiometric determination of fluoride ions in drinking water was developed to include an automatic calibration step, matrix adjustment and sample determination. Also the complex and cumbersome titrimetric procedure for determination of the kappa number (lignin content) in paper pulp, has been automated by using the gravimetric unit and biamperometry. In this last instance, the automatic standardization of the solutions employed in the determination and the complete automation of the recommended kappa number determination procedure, allows a significant reduction in the amount of reagent consumed. The gravimetric approach to these procedures reveals that the same performance is achieved in terms of precision and accuracy when compared with classic volumetry while the cost associated with the automation decreases owing to the use of the same unit to attain automatic management of up to three different solutions.

Spectrophotometric Determination of Fluoride Ion with Zirconium(IV) Salt of Tetraphenylporphine Trisulfonate

Spectrophotometric Determination of Fluoride Ion with Zirconium(IV) Salt of Tetraphenylporphine Trisulfonate

Determination of Fluoride Ion by a Flow Injection Analysis Based on the Formation of a Fluorescent Aluminium-Schiff Base Complex

Abstract In the presence of fluoride ions, aluminium reacts with N-salicylideneethylenediamine to form fluorescent Schiff base complexes. A flow-injection analysis system based on this reaction has been developed for a determination of the fluoride ions at the ppm level. By measuring the fluorescence intensities, the number of fluoride ions could be selectively determined over the range 0.15–10 ppm; 40 samples could be analyzed per hour. The proposed system was applied to an analysis of the fluoried ion in river water.

Direct determination of fluoride ion in mineral spring water with an ion-selective electrode using standard addition method and computer calculation.

鉱泉水中のフッ化物イオンの測定にコンピュータ計算を利用した標準添加法を適応するため,簡易なコンピュータプログラムを作成し,測定上の種々の誤差要因の影響について検討した.温度の影響は25℃を基準としたとき,10℃から47℃の変化に対して検量線法では,+14%～-34%の定量誤差であるのに対し本法は±10%であった.試料水中の塩化ナトリウム濃度の変化は電極電位に大いに影響するが,本法では回収率に影響しない.その他の多くの種類のイオンの共存下でも検量線法に比較すると回収率が良好である.しかし,等量以上のアルミニウムは負の誤差になる.多量の塩類を含んだ鉱泉水での2mgF/1添加では回収率は102%(n=5),RSD 1.7%であった.本法は検量線法より操作が簡単で精度がよく,しかも電位こう配が測定ごとに得られるので結果の信頼性が高まる.

Determination of fluoride ion in animal bone by microdiffusion analysis

A microdiffusion analysis method for the determination of fluoride ion in animal bone sample was established by using a new diffusion cell. The cell is equipped with a water jacket to control the temperature. The space inside the cell is divided by a crossed-beam stand into top and bottom parts. In the bottom part, derivatization of fluoride ion to trimethylfluorosilane (TMFS) by hexamethyldisiloxane as the reagent occurs, with the volatile TMFS being absorbed into alkali placed in an open-top cup supported by the stand. The cell is placed on a magnetic stirrer to rotate the stirring bars in both reaction and absorption solutions. Stirring and elevation of temperature increase the reaction rates. Maintaining the cell at 40 degrees C for 3 h is sufficient for complete extraction of fluoride ion from the bone and its recovery. With our method, more than 10 micrograms/g of fluoride ion in bone can be assayed with a coefficient of variation of less than 3%. The fluoride levels of various rat bones were clarified.

Fibre optic fluorimetric determination of fluoride ions

The reaction between fluoride ions and a complex of calcein blue and zirconium, immobilised on a non-ionic exchange resin Amberlite XAD-4, has been studied with respect to the development of a fibre-optic based fluoride ion sensor. The fluorescence from this complex was enhanced in the presence of fluoride ions, which were detected using optical fibres with the immobilised reagent phase contained in a flow cell. The response to fluoride ions at pH 2.2 was linear in the range 0.11–0.42 mM(2–8 p.p.m.). The reversibility of the reaction has been investigated together with the effect of some foreign ions on the determination of fluoride ions.

Elimination of interference of aluminum ion by a novel resin prepared from desferrioxamine and polyallylamine beads and its application to the determination of fluoride ion

A novel functional resin for the selective adsorption of aluminum was prepared from desferrioxamine(DF) and polyallylamine(PAA) resin. The primary amino group of DF was conjugated with PAA by glutaraldehyde(GA). The resin was found to be effective for the elimination of interference caused by aluminum ion on the determination of fluoride ion. A new determination system for low levels of fluoride ion in the presence of aluminum ion was developed by the use of DF-PAA resin combined with anion exchange resin loaded with alizarin fluorine blue sulfonate; 3-[NN-di(carboxymethyl)aminomethyl)-1,2-dihydroxyanthraquinone-5-sulfonate (AFBS) - lanthanum complex, which was a functional resin for selective collection of fluoride ion.

Gas chromatographic method for the determination of fluoride ion in biological samples. I. Fluoride level in monkey.

A gas chromatographic method for the assay of more than 5 ng/ml of fluoride in biological samples was established. By this method, the fluoride concentrations in monkey plasma, bloodcorpuscles and urine were measured. The fluoride concentration in plasma, which was the lowest before a meal (13-21 ng/ml), increased with time after the ingestions of diet and water. The value reached about twice (22-37 ng/ml) the initial value. Although the fluoride levels before and after a meal differed among animals, the level of each individual monkey was similar to that observed again a week later. The fluoride level in monkey blood-corpuscles was about half the plasma level. Total fluoride recovered in urine for 24 h amounted to 77 to 219 μg. The excreted amounts of fluoride, although they were different among the individuals, were similar in each individual to that observed again after a week. Fluorides in plasma and urine of rat and human were also determined, and compared with those of monkey. The control levels of fluoride in experimental animals determined in this study represent useful basic data for the determination of fluoride produced by metabolism of fluorine-containing drugs.

Simplified determination of fluoride ion in wastewater by an ion selective electrode.

Simplified determination of fluoride ion in wastewater by an ion selective electrode.

Gas chromatographic method for the determination of fluoride ion in biological samples. II. Stability of fluorine-containing drugs and compounds in human plasma.

Our gas chromatogrophic method established previusly has been modified to assay fluoride ion which is released from fluorine-containing compounds and drugs in human plasma. A strongly acidic medium was not necessarily required, though fluoride is usually derivatized to trimethylfluorosilane (TMFS) under such acidic conditions. Trimethylsiylation proceeded in pH 2.5 sulfosalicylate (SSA) buffer. Even labile fluorine-containing compounds were stable in SSA buffer, while they were degraded in a strong acid to form fluofide. SSA was effecitive for buffering HCl which was produced by the reaction of excess reagent, trimthylchlorosilane (TMCS), with H2O. At the same time, SSA in plasma sample served as not only a deproteinizing agent but also a buffer agent for biological materials. By means of the present method, released fluoride in human plasma is assayable even in the presence of labile fluorine-containing compounds. More than 5 ng/ml of fluoride can be quantitated. α-Fluoro-β-alanine, 4-fluoroglutamic acid, 3-difluoroalanine and 5-(trifluoromethyl)uracil released fluoride in human plasma at 37°C in vitro. The amount of fluoride increased with time. On the other hand, no fluoride was liberated from 5-fluorouracil of from compounds of drugs studied other than the above ones.