Determination Of Fluoride In Water Research Articles

A low-cost, colorimeter-based portable device, for rapid, on-spot determination of fluoride in water

ABSTRACT Accurate fluoride measurement in water is required for selecting safe water sources or for treatment options to lessen its impact on public health. A low-cost, portable device has been developed as a rapid fluoride measurement system. It works with an optimal concentration of alizarin red S-zirconium complex (ARS-Zr, the sensor reagent). The device is an LED-phototransistor-based assembly to detect changes in light absorbance at 527 nm, due to monotonically decreasing ARS-Zr concentration with increasing fluoride concentration in water. We have optimised reagent composition in the device, enabling us with a wider fluoride detection range (0.2–9 ppm), rapidly within 4 min; simultaneously ensuring better reagent stability for up to 34 days. Limit of detection (LOD) and limit of quantification (LOQ) of the device are 0.2 and 0.6 ppm, respectively. The device replicates an analytical spectrophotometer’s performance, with a maximum error up to 5% in only a couple of cases. The hand-held device does not give any interference in the presence of even a very high 200 ppm concentration of other common heavy metals (, ,, ,) and anions (, , , , CH3COO−, ), which can be present in water. Fluoride concentration measurement above 1 ppm is unaffected, by even high phosphate concentration up to 10 ppm (typical phosphate level being only ≤ 2.3 ppm). Similarly, for silica concentration up to 10 ppm (typical silica level being 1-30 ppm), fluoride measurement remains unaffected. However, the presence of gives significant interference with fluoride. Overall, we demonstrate the device as an on-spot method, for rapid fluoride measurement, independent of TDS (57.6–151 ppm), pH (6.6–12.5) or conductivity (111.2–283 µS/cm) of the samples, at a low device cost of US$ 25 and reagent cost of 0.44 cents per sample.

Conventional and advanced detection approaches of fluoride in water: a review.

Fluorine is a naturally occurring element found in soil, water, food materials, and natural minerals such as fluorapatite, sellaite, and cryolite and exists as fluoride compounds with other elements because of high reactivity. The exposure of fluoride to the environment and human beings are industrial factors, food, water, and geogenic factors that impact the health of millions of human beings worldwide. Overexposure to fluoride exceeding the permissible limit (1.5mg/l as per WHO) causes several diseases in human beings, such as teeth mottling, thyroid inflammation, dental fluorosis, skeletal fluorosis, lesions in the kidney, and other organs. To overcome the deleterious impact of fluoride, its detection at an early stage is very much required. Therefore, feeling the importance of the same, immense efforts have been made to the selective and sensitive determination of fluoride in water by numerous researchers. This review paper summarizes the various conventional methods such as spectroscopic, ion chromatography, ICP-OES, and gas chromatography-mass spectrometry, their advantages, and drawbacks leading to the development of advanced ready-to-use detection strategies such as stamartphones for on-the-spot fluoride detection. This review paper also discusses future directions, which will assist scientists in achieving a new benchmark in developing a reliable, cost-effective, and user-friendly fluoride detector.

The Potentiometric determination of fluoride in various brands of toothpaste

The potentiometric analysis of the fluoride content (as F-ion) in toothpaste suspension with an ion-selective fluoride electrode is simple, reliable and inexpensive. Very low fluoride ion concentrations (up to 10–5 mol / l) can be determined with a fluoride-selective electrode, whereby the ionic strength of a solution is regulated and the concentration of hydroxide ions and interfering metal ions is controlled. The influence of the pH value and the complex ions of metals can be successfully regulated by the Total ionic strength adjustment buffer (TISAB) solution and by maintaining the pH value in the range from 5.00 to 8.00. The fluoride concentrations of 34 different toothpaste samples of different brands are determined using an ion-selective electrode. The highest value is 1285.85 ppm from Germany (Blend a. Med) and the lowest value is 18.15 ppm from Indonesia (Formula junior). Most of the low values are from Asian countries between (18.15-514.84) ppm, which are less than 600 ppm and this concentration is insufficient for Iraqi prescriptions and World Health Organization (WHO) specifications, the highest Values are between (940.66-1285.85) ppm, from Japan, USA and Germany References Abramowitz, A. (1967) ‘Principles, current practice, and applications of potentiometers based on Poggendorff’s second method’, Review of Scientific Instruments, 38(7), pp. 898–904. doi: 10.1063/1.1720918. Barmes, D. E. (1996) ‘Fluorides and oral health’, Community Dental Health, pp. 3–4. Bereczki, R. et al. (2006) ‘How to assess the limits of ion-selective electrodes: Method for the determination of the ultimate span, response range, and selectivity coefficients of neutral carrier-based cation selective electrodes’, Analytical Chemistry, 78(3), pp. 942–950. doi: 10.1021/ac050614s. Bralić, M. et al. (2001) ‘Fluoride electrode with LaF3-membrane and simple disjoining solid-state internal contact’, Talanta, 55(3), pp. 581–586. doi: 10.1016/S0039-9140(01)00448-9. Chakraborty, M., Pandey, M. and Pandey, P. (2017) ‘Spectrophotometric method vs ion selective electrode for field determination of fluoride in water and complex samples’, Reserch Journal of Chemical Sciences, 7(5)(5), pp. 31–37. Available at: http://www.isca.in/rjcs/Archives/v7/i5/5.ISCA-RJCS-2017-022.pdf. Gao, W., Xie, X. and Bakker, E. (2020) ‘Direct Potentiometric Sensing of Anion Concentration (Not Activity)’, ACS Sensors, 5(2), pp. 313–318. doi: 10.1021/acssensors.9b02523. J, U. (2019) ‘a Review on Effect of Fluoride Concentration in Drinking Water.’, International Journal of Advanced Research, 7(3), pp. 475–478. doi: 10.21474/ijar01/8659. Jasielec, J. (no date) Modelling of potentiometric ion sensors. Julie, L. (1967) ‘A Universal Potentiometer’, IEEE Trans Instr. Meas., IM(3), pp. 187–191. Lennon, M. A. et al. (2004) ‘Rolling Revision of the WHO Guidelines for Drinking-Water Quality’, World Health Organization, (September), pp. 105–116. Available at: http://www.who.int/water_sanitation_health/dwq/chemicals/en/nitratesfull.pdf. Light, T. S. and Cappuccino, C. C. (1975) ‘Determination of fluoride in toothpaste using an lon-selective electrode.’, Journal of chemical education, 52(4), pp. 247–250. doi: 10.1021/ed052p247. Michalski, R. and Mathews, B. (2006) ‘Simultaneous determination of fluoride and monofluorophosphate in toothpastes by supressed ion chromatography’, Central European Journal of Chemistry, 4(4), pp. 798–807. doi: 10.2478/s11532-006-0042-0. Midgley, D. (1987) ‘Limits of detection of ion-selective electrodes: Theory and practice’, Transactions of the Institute of Measurement & Control, 9(1), pp. 25–36. doi: 10.1177/014233128700900105. Radić, J. et al. (2020) ‘Development of the New Fluoride Ion-Selective Electrode Modified with FexOy Nanoparticles’, Molecules (Basel, Switzerland), 25(21). doi: 10.3390/molecules25215213. Seguí Femenias, Y. et al. (2016) ‘Ag/AgCl ion-selective electrodes in neutral and alkaline environments containing interfering ions’, Materials and Structures/Materiaux et Constructions, pp. 2637–2651. doi: 10.1617/s11527-015-0673-8. TOKALIOGLU, Š., KARTAL, S. and SAHIN, U. (2004) ‘Determination of Fluoride in Various Samples and’, Turk J Chem, 28(2), pp. 203–211. Tzimou-Tsitouridou, R., Kabasakalis, B. and Alexiades, C. A. (1985) ‘A new TISAB with Aluminon for fluoride determination in water with ion-selective electrode’, Microchemical Journal, 32(3), pp. 373–382. doi: 10.1016/0026-265X(85)90104-3. Yildiz, Y. et al. (2018) ‘Analytical Chemistry : An Indian Journal Potentiometric Determination of % Fluoride Ion Content ( w / v ) in Toothpastes by Ion Selective Electrode’, 18(August), pp. 0–8. Zohoori, F. V. et al. (2015) ‘Effect of exercise on fluoride metabolism in adult humans: A pilot study’, Scientific Reports, 5, pp. 1–9. doi: 10.1038/srep16905.

Effect of humic substances aggregation on the determination of fluoride in water using an ion selective electrode

The control of drinking water quality is critical in preventing fluorosis. In this study humic substances (HS) are considered as representative of natural organic matter (NOM) in water. We show that when HS aggregate the response of fluoride ion selective electrodes (ISE) may be perturbed. Dynamic light scattering (DLS) results of both synthetic solutions and natural water sample suggest that low pH and high ionic strength induce HS aggregation. In the presence of HS aggregates, fluoride concentration measured by ISE has a reduction up to 19%. A new “open cage” concept has been developed to explain this reversible phenomenon. The interference of HS aggregation on fluoride measurement can be effectively removed by centrifugation pretreatment.

Proposed flow system for spectrophotometric determination of fluoride in natural waters

An environmentally-friendly flow system was developed for the determination of fluoride in natural waters, based on its reaction with zirconium ions and 2-(parasulfophenylazo)-1,8-dihydroxy-3,6-naphthalene-disulfonate (SPADNS). The flow system was designed with solenoid valves in order to increase the versatility and improve the analytical performance, since each device handles the solution independently leading to a more efficient use of reagents. The minimization of reagent consumption and waste generation favors the development of a noteworthy system. Under optimized conditions, a linear response was observed within the range of 0.1–2.2mgL−1, with the detection limit, coefficient of variation and sampling rate estimated as 0.02mgL−1, 4.1% and 60 determinations per hour, respectively. In order to analyze samples containing high fluoride content a wider linear range (0.3–6.6mgL−1) can be obtained by using a low sample flow rate and low sample volume. In comparison with other methods, the proposed system offers advantages such as wider analytical range (1.7–2.2 times), higher sample throughput (1.5–4.0 times) and lower quantification limit (by a factor of 5–68). Along with the consumption of reagents being 20–55 times lower, the generation of wastes is 1.2–3.0 times lower, which contributes to the development of a ‘greener’ system. This method is fast, amenable to automation, environmentally-friendly and of low-cost. In addition, it could be successfully applied to the determination of fluoride in water samples, the results obtained being in agreement with those of the ISE method.

Determination of Trace Fluoride in Water with Flow Analysis-Ion Selective Electrode

Determination of Trace Fluoride in Water with Flow Analysis-Ion Selective Electrode

Design and Development of Novel Sensors for the Determination of Fluoride in Water

The presence of high fluoride content in drinking water is a serious health hazard as it may lead to fluorosis, a serious bone disease. Taking into account of the importance of fluoride an attempt has been made to design and develop simple, low cost, and easy to use sensors for the in situ determination of fluoride in water. Two novel absorption sensors have been fabricated and their characterization done. The first one is a light emitting diode based sensor and the other one is an evanescent wave fiber optic sensor. Reagents prepared using standard methods are mixed with water sample containing fluoride ion, and the peak absorption wavelength is found out. Suitable light sources and photo detectors have been selected, and the sensors are designed to give accurate results over a wide range. A microcontroller based setup has been fabricated for recording the concentration of the measured sample in parts per billion. Both sensors have been used to analyze water samples collected from various sources and regions. The results obtained have been compared with those obtained by using a spectrophotometer used for fluoride measurement and found to have one to one correspondence.

An inter-laboratory comparative study of fluoride determination in water

South Africa is on the brink of implementation of mandatory fluoridation of municipal water following the final approval by Parliament in 2001. The ability to accurately measure fluoride in water is an obvious prerequisite for the safe and effective implementation of water fluoridation. This paper evaluates the current status of fluoride determination in water in South Africa. The study was undertaken by the University of Johannesburg in collaboration with the South African Bureau of Standards as part of their ongoing Water-Check Programme. River water, borehole water, and synthetic water samples were sent to 66 participating laboratories in South Africa in March 2004. The results obtained from the analysis of 7 fluoride-containing samples with varying matrix composition, show that 50% of the laboratories could achieve results that fall between a lower limit of -20% and an upper limit of +20% relative to the true value. The precision (%RSD) for the determination of samples with fluoride concentration at the important level below 0.5 mg/l was poor, ranging from ±20% at 0.5 mg/l to ±100% at 0.1 mg/l. The two major analytical techniques used by the participating South African laboratories were ISE (40%) and IC (36%).. Water SA Vol.32 (3) 2006: pp.365-370

Colorimetric detection of fluoride in an aqueous solution using Zr(IV)–EDTA complex and a novel hemicyanine dye

A new highly sensitive and selective colorimetric method for fluoride determination in water is described. The novel reagent used is a hemicyanine dye ( HC), which forms a stable complex with Zr–EDTA, the fluoride-binding site, through the hydroxyl groups. The hemicyanine-chelating Zr–EDTA complex ( HC–Zr–EDTA) is ready to react with fluoride ion to release HC. This result in remarkable color change of the sensing solutions from red ( λ max = 513 nm) to yellow ( λ max = 427 nm) at pH 4.40. When applied to the colorimetric determination of fluoride ions, a linear range from 3.0 × 10 −6 to 5.0 × 10 −5 mol/L and a detection limit of 2.8 × 10 −6 mol/L with a correlation coefficient of 0.9993 can be achieved under the optimized conditions. Because of the specific affinity of fluorides for the [Zr–EDTA], there is little interference by other ions. This method has been successfully applied to the determination of fluorides in toothpaste samples.

Uncertainty of measurement for the determination of fluoride in water and wastewater by direct selective electrode potentiometry

A procedure to estimate the uncertainty of measurement applied to the fluoride determination of waters and wastewaters matrices by selective electrode potentiometry was implemented based on Eurachem Guide. The major sources of uncertainty were identified as the calibration standard solutions, fluoride concentration obtained by potential interpolation of the regression line and the precision. However the relative uncertainties depend on the anion concentration levels. The methodology proposed was presented to two fluoride concentration levels that are in the range of surface water samples (C sample=1.12 mgF l−1) and of wastewater matrices (C sample=101.4 mgF l−1). The expanded uncertainties calculated were 0.40 and 9.1 mg l−1 for low and high concentration levels, respectively, using the reproducibility uncertainty as precision evaluation. The relative expanded uncertainty was around ±10% for the highest concentration, which can be considered acceptable for the ion selective electrode potenciometric methods and ±36% for the lowest concentrations. In this case the sample fluoride content is very close to the limit of quantification which has a relative uncertainty of about ±30%. If the repeatability was used in spite of duplicate analysis the same conclusions were obtained (C sample=1.12 ± 0.39 mgF l−1 and C sample=101.4 ± 7.0 mgF l−1).

A colorimetric method for fluoride determination in aqueous samples based on the hydroxyl deprotection reaction of a cyanine dye

A new highly sensitive and selective colorimetric method for fluoride determination in water is described. The novel reagent for this method is a cyanine dye (C 1) on which the hydroxyl group has been protected by reaction with tert-butyldimethylsilane (TBS) to form the silanated dye, C 2. C 2 is selectively attacked by fluoride ions to reform C 1. C 1 has an absorption maximum at 600 nm with a molar absorptivity of about 200,000. Under optimized conditions, absorbance at 600 nm is proportional to fluoride concentration up to about 1 × 10 −4 mol/L with a detection limit of 1.0 × 10 −7 mol/L. Because of the specific affinity of fluoride for the TBS functional group on C 2, there is little interference by other ions. The method has been successfully applied for fluoride determinations in local rainwater samples. Results determined by the proposed method agree favorably with those determined by a fluoride ion selective electrode method.

リン酸水素カルシウム二水和物（ＤＣＰＤ）の転化反応を用いた地下水中微量フッ化物の簡易定量法

Ion-selective electrodes (ISE) are widely utilized for the determination of fluoride in water. For the determination of trace amounts of fluoride in groundwater, a pre-concentration process is required because of lack of sensitivity of ISE to fluoride. Calcium hydrogenphosphate dihydrate (DCPD) efficiently reacts with fluoride ion in a solution to form fluorapatite (FAp). The aim of this study was to develop a simplified method of determination of trace amounts of fluoride in groundwater using DCPD. In this paper, a suitable pH range for measuring fluoride using ISE was assessed on the basis of chemical equilibrium. It was found that the suitable pH for fluoride determination by ISE is 5.5-7.0, and FAp can be dissolved in this pH range by the complex-forming reaction of CyDTA. From the obtained results, a simple method for determining trace amounts of fluoride in groundwater has been established. Fluoride in a 100 ml water sample is quantitatively fixed as FAp using 0.10 g of DCPD at 60°C for 1hr. The fluoride that separated as FAp is dissolved in a 10 ml solution containing NaCl, CyDTA and HEPES. The amount of fluoride ion in the solution is easiliy measured by using ISE.

Determination of Fluoride in Water by Reversed-Phase High-Performance Liquid Chromatography using F?-La3+-Alizarin Complexone Ternary Complex

A method for the determination of fluoride by reversed-pkase, high-performance liquid chromatography (RP-HPLC) is described. Fluoride, La 3, and alizarin complexone form F-La3+- alizarin complexone ternary complex, which is separated from the matrix on a RP, Ultrasphere C-18 column (250 x 4.6 mm, 5 mum) using methanol-water (19:81, v/v) mobile phase at 1.00 mL min(-1) - detection at 568 nm. The calibration graph was linear from 1.0-150 ng mL(-1) for fluoride with a correlation coefficient: 0.9993 (n = 6). The detection limit was 0.2 ng mL-1. The method was successfully applied to the determination of fluoride in river and tap water. Recovery was: 94-102%, RSD in the range: 1.9-3.6%.

Fast spectrophotometric determination of fluoride in ground waters by flow injection using partial least-squares calibration

The presence of sulphate constitutes a serious interference in the usual zirconium lake-based spectrophotometric method for the determination of fluoride in water. In this report, full spectral data have been recorded for the zirconium lake of 2-(parasulfophenylazo)-1,8-dihydroxy-3,6-naphthalene-disulfonate (SPADNS) in the simultaneous presence of fluoride and sulphate, as obtained with a flow injection system with a diode-array detector. The information has been processed with partial least-squares (PLS) multivariate calibration. Adequate modeling using a sixteen-sample calibration set allows fluoride to be determined in ground waters by the automated flow injection method, even in the presence of sulphate in concentrations up to 1000 mg l −1. In the calibration range 0–1.50 mg l −1 for fluoride, the limit of detection is 0.1 mg l −1. The fluoride contents in real samples, as determined with the present method, were satisfactorily compared with those provided by ion selective potentiometry.

Electrochemistry "Discovery" Course for Undergraduates

We developed a chemistry selected topics course at Central State University, Introduction to Laboratory Techniques in Electrochemistry to: (1) give undergraduates hands-on experience with electrochemical measurements, (2) prepare students for summer research in Fuel Cell and Battery technology. Since students learn by doing, the course is suitable for undergraduates from sophomore to senior levels. Students complete 6 laboratories, based on a less is more philosophy which emphasizes analytic and creative process rather than mandatory topical coverage. Eight electrochemical experiments are available: Construction of Zinc-Copper battery stacks, Lead Acid Battery discharge-charge cycles, Conductimetric titration of aspirin with Ammonium Hydroxide, Ion Selective Electrode determination of Fluoride in water, Cyclic Voltammetry of Potassium Ferricyanide solution, Cyclic Voltammetry of Sulfuric acid on Platinum working electrode, Anodic Stripping Voltammetry of Lead ion in solution, Differential Pulse Pola...

The determination of fluoride in water in the presence of organic acids and iron using a fluoride-selective electrode

Surface waters in Scotland, notably from upland catchment areas, are commonly enriched in iron and organic acids. This study investigated the impact of these species on the direct potentiometric determination of fluoride using a fluoride-selective electrode. As the electrode technique is commonly used to monitor the fluoride content of potable waters, it is important that these effects are evaluated if such waters are to be fluoridated.The determination method used was that defined by Nicholson (1983) and Nicholson and Duff (1981) to minimise errors. This employs the TISAB III-TAC buffer system with the following composition (in 1L): 58.0 g sodium chloride, 57.0 mL glacial acetic acid, 4.0 g CDTA, 243.0 g tri-ammonium citrate adjusted to pH 5.4 with 10 M sodium hydroxide. Experimental solutions of fluoride with organic acid or iron were prepared, and the effect on fluoride concentration determined for each combination. Concentrations used: fluoride: 0.1, 1.0 mg L(-1); humic acid: 5, 10, 100, 1000, 10,000 mg L(-1); oxalic acid: 5, 10, 100, 1000, 10,000 mg L(-1); iron(III): 1, 10, 100, 500 mg L(-1);Humic acid (HA) concentrations had no impact on the determination of fluoride at the 1.0 mg L(-1) level. However, with 0.1 mg L(-1); F(-), an increase in the apparent fluoride concentration was observed when HA > 1,000 mg L(-1); this increased with increasing HA content to a maximum of ∼600%. Oxalic acid (OA) generally had no impact on the fluoride determinations at the 1.0 mg L(-1); level, but at an OA concentration of 10,000 mg L(-1); fluoride concentrations were reduced by ∼50%. At 0.1 mg L(-1) F(-), increasing OA concentrations produce a steady increase in the fluoride concentration of up to 200% with 1,000 mg L(-1); OA, greater OA contents produce a fall in the fluoride content. Iron had no effect on the fluoride determinations at both the 0.1 and 1.0 mg L(-1) levels.The causes of the apparent increases in fluoride concentration have not been determined, although fluoride contamination by the reagents has been ruled-out. However, the results demonstrate that the defined method and buffer system is suitable for the determination of fluoride in the presence of iron and organic acids at naturally occurring levels, and that fluoride will not be masked from detection.

Segmental flow injection with ion-selective electrodes for the determination of fluoride in water

A flow analyser with enhanced sampling frequency combining the features of flow-injection and continuous-flow analysis is described. Parameters of the analyser were optimized to ensure the highest rate of analysis allowed by the bubble-through flow cell with fluoride-selective electrodes. Fluoride was determined in 0.1-ml water samples with a sampling rate as high as 720 h −1 and a relative standard deviation better than 1%.

Polarographic determination of fluoride using the adsorption wave of the Ce(III)-alizarin complexone-fluoride complex

A very sensitive electrochemical method for trace measurement of fluoride in water is discussed. The complex of cerium(III) with alizarin complexone (ALC) and fluoride ion is adsorbed at the dropping mercury electrode. In cathodic sweeps, the peak height is directly proportional to the concentration of fluoride over the range 8 × 10 −8-5 × 10 −6 M (1.5 × 10 −9–9.5 × 10 −8 g/ml), and the detection limit is 5 × 10 −8 M (9.5 × 10 −10 g/ml). The proposed method was applied to the determination of fluoride in water.

Indirect inductively coupled plasma atomic emission determination of fluoride in water samples by flow injection solvent extraction

An indirect determination of fluoride in water by inductively coupled plasma atomic emission spectrometry combined with flow injection coupled with solvent extraction is reported in this paper. A manifold for rapid determination of fluoride has been designed that uses a single coil for complex formation and extraction. The method involves the formation of lanthanum/alizarin complexone/fluoride complex and its extraction into hexanol containing N,N-diethylaniline. The concentration of fluoride is determined indirectly by introduction of the organic layer into the plasma and measurement of the emission intensity of the La II 333.75-nm line. The optimum experimental conditions for the determination are described. A coiled groove phase separator fitted with a grid and PTFE porous membrane was used in this work. The sampling rate was 36 samples per hour and the calibration graphs were linear from 0.03 to 1.3 micrograms/mL. The relative standard deviation found was 2.16% for 200 microL of 1 microgram/mL of fluoride. The method is selective and has been applied satisfactorily to the determination of fluoride in water samples.

Indirect Spectrophotometric Determination of Fluoride In Water With Zirconium-Spadns By Flow Injection Analysis

Abstract The zirconium-SPADNS method for the determination of fluoride based on the effect of fluoride ion on the color system (Zr-SPADNS), has been adapted to the continuous flow spectrophotometry. A manifold consisting of two lines was used. the decrease in the absorbance of Zr-SPADNS reagent at 590 nm is linear with fluoride concentration in the range 0.00-3.5 ppm. the method has a detection limit of 0.02 ppm fluoride. At a sampling rate of 50 determinations per hour, the precision was about 1% relative standard deviation. the method is applied to the determination of fluoride in natural water samples. the good agreement between the results obtained by this method and those obtained by a potentiometric method using a fluoride ion-selective electrode, show that the new method is potentially suitable for routine analysis. the effects of reaction conditions, flow parameters, and interferences on the FIA-spectrophotometric signals are reported. amount of interfering ion is present in quantity great enough ...