Method For Determination Of Fluoride Research Articles

Validation of Ion Chromatographic Method for Determination of Standard Inorganic Anions in Treated and Untreated Drinking Water

An ion chromatographic method for determination of fluoride, chloride, nitrate and sulphate in untreated and treated drinking waters was described. An automated 850 IC Professional, Metrohm system equipped with conductivity detector and Metrosep A Supp 7-250 (250 x 4 mm) column was used. The validation of the method was performed for simultaneous determination of all studied analytes and the results have showed that the validated method fits the requirements of the current water legislation. The main analytical characteristics were estimated for each of studied analytes: limits of detection, limits of quantification, working and linear ranges, repeatability and intermediate precision, recovery. The trueness of the method was estimated by analysis of certified reference material for soft drinking water. Recovery test was performed on spiked drinking water samples. An uncertainty was estimated. The method was applied for analysis of drinking waters before and after chlorination.

A Simple and Sensitive Fluorescence Method for Fluoride Determination in Dietary Supplements, Fluorinated Salts, and Tea

Fluoride at low concentrations is vitally important for human health, although its slight overdosage can lead to some adverse effects in various organs. A fluorescence method for the analysis of fluoride in different foodstuff has been proposed. It is based on the formation of the mixed-ligand complex of Zr(ІV) with Morin and fluoride. In general, the fluorescence of the complex shows a rise at 510 nm, as the concentration of the fluoride in solution grows. The detection limit and the range of linearity were found to be 0.1 μmol L−1, and 0.3–10 μmol L−1, respectively. This method was applied to analyze dietary supplements, іodized-fluorinated salts, and various teas, such as green, black, white, granulated ones, and tea in bags. The effect of brewing time, repeated brewing, and packaging materials on the concentration of the fluoride in tea infusions has been investigated. The new method proved to be very simple, sensitive, reproducible, accurate, and reliable. Moreover, this method has a powerful potential for the determination of fluoride in other food samples.

Field method for estimation of fluoride in drinking groundwater by photometric measurement of spot on aluminium quinalizarin reagent paper

A simple field method for determination of fluoride in drinking water using handmade fluoride reagent paper impregnated by aluminium quinalizarin complex was developed. Fluoride reacts with the impregnated reagent paper to release the free ligand with new colour, orange different from that of the complex. The change in the colour, which is proportional to the amount of fluoride, was measured by the Arsenator. The functionality of the Arsenator which is based on a photometric measurement of spot on the reagent paper is expanded to analyse fluoride. The method allows a reliable determination of fluoride in the range 0.0–2.0mgL−1.Further spectrophotometric determinations of fluoride showed that Beer’s law is obeyed in the range of 0.3–5.0mgL−1 at 553nm. Sensitivity, detection limit, quantitation limit, and the percentage recovery of 1.5mgL−1 fluoride were found to be 0.117μgmL−1, 0.1mgL−1, 0.3mgL−1, and 101.2 respectively.

Determination of fluoride in plant material using microwave induced oxygen combustion

Fluorine is essential in human and/or animal nutrition, thus it is important to know its concentration in a diet. One of the important sources of fluorine for humans is tea, containing relatively high amounts of this trace element. A method for fluoride determination in various kinds of tea using microwave supported sample preparation in a high pressure oxygen atmosphere followed by potentiometry with a fluoride ion-selective electrode were described. The parameters of the microwave device for such combustion procedure were checked and optimised in order to find settings ensuring complete sample combustion and/or absorption of the analyte in the absorption solution. For the ion-selective electrode measurement, the technique of standard addition was chosen. The Nernstian slope of the fluoride ion-selective electrode was measured and calculated in the concentration range in which the potential of samples occurred. Concentrations of fluorides in tea in the range from 24.5 mg/kg to 254.5 mg/kg were found. In order to check the accuracy of the method certified reference materials were used. The precision expressed as the relative standard deviation ranged from 3.7% to 15.9%. The method is fast, accurate and reliable for this kind of analysis.  

Determination of fluoride in human whole blood and urine by gas chromatography-mass spectrometry

We developed a simple and sensitive method for determination of fluoride in human whole blood and urine using gas chromatography-mass spectrometry (GC-MS). Fluoride was alkylated with pentafluorobenzyl bromide in a mixture of acetone and phosphate buffer (pH 6.8). The derivative obtained was analyzed by GC-MS in the positive-ion electron-impact mode. The lower limit of detection for the compound was 0.5 mg/l for both matrices. The calibration curve for fluoride was linear over the concentration range of 1–100 mg/l. The precision and accuracy of the method were evaluated, and relative standard deviation was within 10%. Using this method, levels of fluoride in whole blood and urine were determined in a case of poisoning caused by hydrofluoric acid exposure.

Determination of fluoride in toothpaste using headspace solid-phase microextraction and gas chromatography–flame ionization detection

A new method for determination of fluoride in toothpaste employing the headspace solid-phase microextraction (HS-SPME) followed by gas chromatography/flame ionization detection (GC/FID) has been proposed. It is a development of the method for determination of fluoride using trimethylchlorosilane (TMCS) as the derivatization reagent to form trimethylfluorosilane (TMFS), with the liquid/liquid extraction (LLE) step replaced by HS-SPME. To introduce the latter, it was necessary to determine the conditions of the reaction and to optimize the two stages of the SPME procedure: extraction and desorption. The parameters of the SPME analysis using carboxen/polydimethylsiloxane (CAR/PDMS) fiber were defined and compared with the corresponding ones for the LLE method, used as a reference. Also, these two methods were compared with respect to their linearity, precision, and accuracy. Results from toothpaste analyses using these two methods were highly correlated, indicating the potential to use the SPME extraction as an inexpensive and solventfree alternative to the LLE method.

Determination of Fluoride in Wine by Fluoride Selective Ion Electrode, Standard Addition Method: Collaborative Study

The accuracy, precision, and reproducibility of a rapid method for determination of fluoride in wine, using a fluoride selective ion electrode, were established by a collaborative study involving 12 laboratories, 5 in Europe and 7 in the United States. The laboratories assayed 6 Youden pairs of fluoride-fortified, red and white wine samples with fluoride concentrations ranging from 0.2 to 3.0 mg/L. The relative standard deviations of repeatability ranged from 1.94 to 4.88%; relative standard deviations of reproducibility ranged from 4.15 to 18.40%. HORRAT values ranged from 0.30 to 0.97. The average recovery was 99.97%. Based on the statistical results of this collaborative study, the Study Director recommends that this method be adopted First Action.

Highly Sensitive Methods for Determination of Fluoride in Biological Samples

A total of 40 samples of shell ashes from chicken eggs and 15 samples of chicken plasma have been investigated for amounts of fluoride. Two different methods have been applied. Egg samples were analysed with a spectrophotometric method (Alizarin:cerium:fluoride complex with detection at λ = 620 nm), following prior distillation of the samples in sulfuric media. Plasma samples were analysed by suppressed ion chromatography (IC) with conductivity detection. In this case, it was necessary to develop a cleaning method for the samples before their injection into the chromatographic system. The detection limits obtained were 25 ng mL−1 for the colorimetric method and 50 ng mL−1 in the case of the chromatographic method. Both methods were successfully applied to the analysis of the samples, and the obtained results were in accordance with the results obtained with the ion selective electrode (ISE) method. On the other hand, the proposed methods turn out to be a sensitive alternative when problems with sample size or cationic interferences are present.

Extraction-Spectrophotometric Method for Determination of Fluoride in the Range of Microgram per Liter in Natural Waters

In this study a new extraction–spectrophotometric method for the determination of fluoride ion in natural waters has been presented by use of octyl chemically bonded solid phase extraction (SPE) cartridge. In this method at first aluminium–oxinate chelate is adsorbed on SPE cartridge, then the water sample (containing fluoride ion) is passed through the SPE device. The excess of oxine on the sorbent is washed with acetate buffer and finally the residual of aluminium–oxinate chelate on the sorbent is eluted by ethanol and its absorbance is read at 375 nm. The decrease of adsorbed aluminium–oxinate chelate on sorbent is proportional to the fluoride ion concentration in the water samples. The detection limit of this method is 80 ng/ml and the linear dynamic range is between 0.1–2 µg/ml. Sensitivity of the method is excellent and absorbance variation for each µg/ml fluoride ion is 0.6 (approximately equal to Eriochrome cyanine R-zirconium standard method and ten times better than the Alizarin complexon standard method). Results of this method have good agreement with the Eriochrome cyanine R-zirconium standard method. Also this method has less interferences as compared with SPADNS standard method.

Determination of fluoride in bone by aluminum monofluoride molecular absorption spectrometry

Phosphate, by virtue of its intrinsic capacity to form complexes with aluminum, interferes extensively with the aluminum monofluoride molecular absorption spectrometric (MAS) method for fluoride. However, it has now been found that in the presence of calcium there was no such interference when the ratio of phosphate to calcium was similar to that in calcium phosphate. On the other hand, there was an enhancement of the AlF signal. This observation is now the basis of an AlF MAS method for determination of fluoride in bone ash, which is essentially calcium phosphate. The procedure involves injecting formic acid solutions of bone ash and of calcium phosphate-fluoride standards into a graphic furnace and obtaining the AlF absorbances at 227.5 nm. Results of analyses of bone samples obtained by the AlF MAS method are in excellent agreement with those obtained with the fluoride electrode.

A rapid spectrophotometric method for determination of fluoride in silicates with the zirconyl-xylenol orange complex

A critical study has been made of the effect of acid concentration and of polymerized and depolymerized zirconyl ions on the formation of ZrO-XO complexes and their stabilities. At an optimum acidity of 0.5–0.6 M hydrochloric acid, most of the common cations occurring in silicates do not interfere. Maximum colour development is almost instantaneous for the depolymerized ZrO-XO complex, but takes a few hours for the polymerized complex; the colour is stable for several hours. The absorbance is highest for the depolymerized ZrO-XO complex and decreases with an increase in polymerization of the zirconyl ions. Dissolved oxides of nitrogen affect the stability of the ZrO-XO complex but can be eliminated with urea. A simple, rapid and sensitive spectrophotometric method has been worked out for use of this complex in determination of fluoride in silicates, without separation, after fusion of the sample with sodium hydroxide at 450–550°.

An improved method for the spectrophotometric determination of fluoride by addition of sodium dodecyl sulphate to the fluoride/lanthanum (III)/Alizarin fluorine blue system

The conventional spectrophotometric method for the determination of fluoride, based on the fluoride/lanthanum(III)/alizarin fluorine blue ternary complex, is improved by addition of sodium dodecyl sulphate. In 15% (v/v) acetone medium, the absorbance of the binary reagent complex is decreased and the reaction time is only 3 min under sonication. Beer's Law is obeyed at 574 nm for fluoride concentrations in the ranges 0.075–0.30 and 0.20–1.2 mg 1 −1; the apparent molar absorptivities are (1.6 ± 0.1) × 10 4 and (1.5 ± 0.1) × 10 4 mol −1 cm −1 fluoride levels, respectively. This method is applied to the determination of fluoride in bottled mineral waters.

Determination of Fluoride in Blood Samples for Analysis of Alcohol

ABSTRACTA simple, rapid method for determination of fluoride, used as a preservative in blood samples for analysis of alcohol2, is described. Using ion-selective electrodes and 0.1 mL of blood, the fluoride concentration can be determined within 5% of the actual value.

Application of Fluoride Ion-Specific Electrode Method for Determination of Fluoride in Foods

Application of Fluoride Ion-Specific Electrode Method for Determination of Fluoride in Foods

Evaluation of Agreement Among Routine Methods for Determination of Fluoride in Vegetation: Interlaboratory Collaborative Study

Abstract An interlaboratory collaborative study was conducted to evaluate the performance of methods and laboratories for the measurement of fluoride in vegetation. Samples of 8 plant species containing about 5-200 ppm fluoride were distributed to 40 participants who were instructed to use their routine methods of analysis. Methods which had sufficient participants to allow the inclusion of results in statistical analyses were classified into 3 categories: (1) Willard-Winter method (similar to the AOAC official final action method); (2) semiautomated and potentiometric methods (similar to the 2 AOAC official first action methods); and (3) potentiometric analysis with prior ashing, fusion, and/or distillation (not an approved method). There was a significant interaction of methods with samples caused by 3 of the 8 samples. In the other 5 samples, the Willard-Winter and semiautomated methods gave higher mean values for fluoride content than did the 2 potentiometric methods. Despite considerable improvement in speed and simplicity of fluoride analyses during the last decade, agreement between laboratories has not improved because of the variety of methods and techniques in use, the inherent differences between methods, and, apparently, poor laboratory quality control.

A comparison of ion-chromatographic and potentiometric techniques for the determination of gaseous and particulate fluoride in air

The methods of ion-chromatography and potentiometry for the determination of fluoride in air and airborne dust are described. An ionchromatographic method for the direct determination of fluoride in absorption solutions and filter extracts has been developed. Results are compared with those of a modified potentiometric method using an ionselective electrode. Fluoride concentrations in different air samples from the working atmosphere and in dust from aluminium reduction cell ventilation air were determined. The use of aluminium complexing agents for the potentiometric method is discussed and different quantification methods for this technique have been investigated. Results of both techniques were compared using known standards from an intercalibration study and real samples from an aluminium plant, with fluoride concentrations of 2–300 ppm. The detection limit for the two methods is on the order of 0.1 ppm.

Sulphonated alizarin fluorine blue (AFBS). Part III. Lanthanum(III) complexes of 1-hydroxyanthraquinone-2-sulphonate, alizarin-5-sulphonate and AFBS, the fluoride complex of AFBS-lanthanum and a suggested method for fluoride determination

An attempt is made to understand the reaction for ternary complex formation between sulphonated alizarin fluorine blue (AFBS), lanthanum and the fluoride ion through study of complex-forming reactions between lanthanum and 1-hydroxyanthraquinone-2-sulphonate (HA2S), alizarin-5-sulphonate (A5S) and sulphonated alizarin fluorine blue, successively. Comparison of experimental molar-ratio and Job plots with those derived from theory reveals that HA2S forms 1:1 and 1:2 lanthanum-HA2S complexes of K11abs= 1.85 × 107 l mol–1 and K12abs= 1.29 × 107 l mol–1; A5S forms 1:1, 1:2 and 2:2 lanthanum-A5S complexes and AFBS forms 1:1, 2:1 and 2:2 lanthanum-AFBS complexes. Fluoride ions react to form FR and FR2 complexes, where R represents a particular mixture of AFBS-lanthanum complexes. Conditions under which AFBS can best be used for the determination of fluoride are explored and such an analysis is compared statistically with one using the original alizarin fluorine blue; the latter performs well. The use of other lanthanoid ions is investigated.

Collaborative Study of Ion Selective Electrode Method for the Direct Determination of Fluoride in Feeds

Abstract A rapid and precise method for the determination of fluoride in feeds employs HC1 extraction of the sample. Acetate buffer and sodium citrate are added to control pH and ionic strength. The amount of fluoride is calculated from a standard curve after measuring the potentials of standard and sample solutions. Eight collaborators participated in the study of the method. Statistical values on 3 pairs of samples were calculated. The standard deviation, precision, coefficient of variation, and bias, respectively, were: Pair 1, 0.005071, 0.001763, 3.09, 0.0034; Pair 2, 0.037122, 0.006475, 1.82, 0.0258; Pair 3, 0.034587, 0.013021, 2.63, 0.0227. The results from the proposed method agreed favorably with the values obtained by using the official final action AOAC method, 7.089. The average and standard deviation, respectively, for individual samples by the proposed method were: Sample 3, 0.049, 0.0029; Sample 4, 0.059, 0.0021; Sample 5, 0.334, 0.0114; Sample 6, 0.341, 0.0101; Sample 7, 0.511, 0.0219; Sample 8, 0.492, 0.0237. By the official method the values were: Sample 3, 0.049, 0.0041; Sample 4, 0.058, 0.0029; Sample 5, 0.334, 0.0055; Sample 6, 0.331, 0.0082; Sample 7, 0.517, 0.0183; Sample 8, 0.499, 0.0175. The ion selective electrode method has been adopted as official first action.

Field method for the volumetric determination of fluoride in water using SPADNS and thorium nitrate

Field method for the volumetric determination of fluoride in water using SPADNS and thorium nitrate

Microdetermination of the fluoride ion using an amplification reaction

A new simple, rapid and accurate amplification micro method for fluoride determination is described. It is based on the reaction between the sparingly soluble calcium iodate and the fluoride ion. After adding isopropyl alcohol to the solution, so that its final concentration is 65%, and filtering, an equivalent amount of the iodate is obtained. The latter is titrated iodometrically resulting in a six-fold amplification of the titre. The method is reproducible over a range from 0.4–8 mg fluoride ion. The mean recovery is 99.69%, after applying a correction factor due to potassium iodate solubility.