Fluoride In Water Samples Research Articles

Deciphering geochemical fingerprints and health implications of groundwater fluoride contamination in mica mining regions using machine learning tactics.

The contribution of mica mining activities to fluoride (F-) contamination in groundwater has been chased in this study. For the purpose, groundwater samples (n = 40, replicated thrice) were collected during the post-monsoons (September-October) from a mica mining area in the Tisri block of Giridih district, Jharkhand. The study has employed a synergy of classical aquifer chemistry, statistical approaches, different indices, Self-Organising Maps (SOM), and Sobol sensitivity index (SSI) to unveil the underlying aquifer chemistry, identify the impacts of mining activities on groundwater quality and its associated health hazard. Fluoride levels varied from 0.34 to 2.8ppm, with 40% of samples exceeding the World Health Organization's permissible limit (1.5ppm). Physicochemical analysis revealed significant differences in electrical conductivity (EC), total dissolved solids (TDS), total hardness (TH) and major ion concentrations (Na+, HCO3-, Ca2+) between fluoride-contaminated (FC) and fluoride-uncontaminated (FU) groups. Higher Na+ and HCO3- associated with F- contaminated samples, were indicative of silicate weathering and carbonate dissolution as primary geogenic sources for this ion. Health risk assessment (HRA) revealed hazard quotient (HQ) values exceeding unity, indicating non-carcinogenic risks, particularly for children in most samples from group FC. The mean Water Quality Index (WQI) of FC group (156.76 ± 7.30) was significantly higher (p < 0.05) than group FU indicating of its unsuitability. SOM could accurately (80%) predict presence of fluoride in water samples based on other major ions. Sobol sensitivity analysis successfully identified fluoride concentration and body weight as most impactful parameters affecting human health. The integration of advanced modelling techniques and geospatial analysis as Inverse Distance Weightage (IDW) maps has provided a robust framework for ongoing groundwater quality monitoring in mining-affected regions and can help proactive intervention in risk-prone areas. Overall, this comprehensive study takes us a step ahead towards ensuring safe drinking water access for the global community.

Determination of trace fluoride in water samples by silylation and gas chromatography/mass spectrometry analysis.

Due to the ubiquity of fluorides and the small gap between a safe dose and a harmful one, it is necessary to develop a robust analytical method for determination of fluoride ions in various water samples with complex matrices. Silylation of the fluoride ion was carried out by treatment with hydrochloric acid and phenyldimethylchlorosilane at room temperature. The formed phenyldimethylfluorosilane was detected by gas chromatography/mass spectrometry (GC/MS). Under the optimized conditions, linearity in the analytical method ranged from 0.050 to 5.0 μg/mL for the fluoride ion with R2 >0.9999. Reasonable reproducibility was obtained with the intraday relative standard deviation (RSD) (N = 5) of 2.04% and interday RSD (N = 5) of 3.75% at the concentration of 0.10 μg/mL. The developed method has been successfully applied to determine the fluoride ion in real water samples, including waste water samples, with the recovery between 81.12% and 113.04%. A robust method for the determination of the fluoride ion has been developed by silylation with phenyldimethylchlorosilane and GC/MS analysis. The established method showed good anti-interference and precision, and it has been applied for determination of the fluoride ion in various water samples.

A reaction-based approach for fluorescence sensing of fluoride through cyclization of an O-acyl pyrene amidoxime derivative

A novel reaction-based O-acyl pyrene amidoxime derivative was easily synthesized from pyrene-1-carbaldehyde in three step and fully characterized. The sensing ability of the receptor towards various anions were investigated. The receptor exhibited distinct fluorescent behavior by a 45-fold increase in the emission intensity upon reacting with fluoride. The fluoride-induced cyclization reaction of the receptor led to formation of a highly fluorescent pyrene 1,2,4-oxadiazole derivative. However, other anions such as Cl−, Br−, I−, AcO−, NO3−, ClO4−, H2PO4− and HSO4− could not exhibit a remarkable increase in emission intensity. The fluorescence quenching of the receptor was explained by photoinduced electron transfer mechanism. The suppressing of photoinduced electron transfer, which was triggered by cyclization reaction between O-acyl amidoxime moiety and fluoride, led to an off-on type blue emission output. Fluoride could be detected with the present receptor up to a lower concentration limit down to 1.36 μM. The fluorescence response of the receptor was rationalized by time-dependent density function theory calculations. Moreover, a practical application showed that the receptor could be exploited as a test paper in the fluorescence detecting for fluoride in water samples.

Influence of Surface Coating on Fluoride Removal by Magnetite

ABSTRACTAl(OH)3- and ZrO(OH)2-coated magnetites were prepared and used for fluoride removal from aqueous samples. The influence of pH, sorbent mass, and ions such as chloride, sulfate, and phosphate on the removal of fluoride was characterized. The sorption process was highly pH dependent, and the optimal sorption was obtained from pH 4 to 5 for ZrO(OH)2- and pH 4 to 7 for Al(OH)3-coated magnetites. The sorption isotherm was well described by the Langmuir equation for the sorbents. The maximum adsorption capacity of ZrO(OH)2-coated magnetite (57.47 mg-F g−1-sorbent) was higher than for Al(OH)3-coated magnetite (23.87 mg-F g−1-sorbent). The ion-exchange reaction occurred in 5 min and more than 99% of fluoride was removed from solution. When the ZrO(OH)2-coated magnetite was used, the presence of foreign ions negatively affected the fluoride removal. The prepared sorbents showed an excellent performance for the removal of fluoride in water samples.

Monitoring of fluoride in water samples using a smartphone

In several parts of India, groundwater is the only reliable, year round source for drinking water.Prevention of fluorosis, a chronic disease resulting from excess intake of fluoride, requires the screening of all groundwater sources for fluoride in endemic areas. In this paper, the authors present a field deployable colorimetric analyzer based on an inexpensive smartphone embedded with digital camera for taking photograph of the colored solution as well as an easy-fit, and compact sample chamber (Akvo Caddisfly). Phones marketed by different smartphone makers were used. Commercially available zirconium xylenol orange reagent was used for determining fluoride concentration. A software program was developed to use with the phone for recording and analyzing the RGB color of the picture. Linear range for fluoride estimation was 0–2mgl−1. Around 200 samples, which consisted of laboratory prepared as well as field samples collected from different locations in Karnataka, India, were tested with Akvo Caddisfly. The results showed a significant positive correlation between Ion Selective Electrode (ISE) method and Akvo Caddisfly (Phones A, B and C), with correlation coefficient ranging between 0.9952 and 1.000. In addition, there was no significant difference in the mean fluoride content values between ISE and Phone B and C except for Phone A. Thus the smartphone method is economical and suited for groundwater fluoride analysis in the field.

Poly(3-aminophenylboronic acid)-reduced graphene oxide nanocomposite modified electrode for ultrasensitive electrochemical detection of fluoride with a wide response range

Here we develop a novel approach for electrochemical detection of fluoride by poly(3-aminophenylboronic acid)-reduced graphene oxide (PAPBA-RGO) nanocomposite modified electrode. In this approach, the proposed electrode was fabricated by a two-step procedure, including direct electrodeposition of graphene oxide and electrochemical polymerization of 3-aminophenylboronic acid. Electrochemical detection of fluoride by PAPBA-RGO nanocomposite modified electrode was performed based on the variation of reduction peak current of ferricyanide, which was induced by the binding between boronic acid groups of PAPBA and fluoride. The obtained results displayed that reduction peak current of ferricyanide decreased with increasing concentration of fluoride, and two good linear relationships between the reduction peak current and the logarithm of fluoride concentration were obtained in the concentration range of 1×10−10 to 1×10−5M and of 1×10−5 to 1×10−1M, respectively. The limit of detection of the proposed approach was 9×10−11M. The interference of other competing ions including Cl−, Br−, I−, NO3−, ClO4−, Ac− or SO42− was negligible. Furthermore, the PAPBA-RGO nanocomposite modified electrode was employed for detection of fluoride in water samples.

Spectrophotometric Determination of Fluoride in Groundwater Using Complexes of Flavonoid Chrysin

A simple spectrophotometric method is developed for determination of fluoride in drinking water by using complexes of chrysin. The method is based on the reaction of the coloured complexes with fluoride where its colour changes, due to the formation of the colourless fluoride complex and liberating of the free ligand, is dependent on the concentration of fluoride in water samples. The molar absorptivity for the complexes at the wavelength of maximum absorption in the visible region, 371 nm is 2.75 × 103 L mol-1 cm-1. The method allows a reliable determination of fluoride in the range 0.3─3.0 mg L-1 which is compatible to WHO limit value of 1.5 mg L-1. The sensitivity, detection limit, quantitation limit, and correlation coefficient for the method were found to be 0.211 μg mL-1, 0.1 mg L-1, 0.3 mg L-1, and 0.9914 respectively. The percentage recovery of 1.5 mg L-1 fluoride is 101.3.

Spectrophotometric Determination of Fluoride in Groundwater Using Complexes of Flavonoid Chrysin

A simple spectrophotometric method is developed for determination of fluoride in drinking water by using complexes of chrysin. The method is based on the reaction of the coloured complexes with fluoride where its colour changes, due to the formation of the colourless fluoride complex and liberating of the free ligand, is dependent on the concentration of fluoride in water samples. The molar absorptivity for the complexes at the wavelength of maximum absorption in the visible region, 371 nm is 2.75 × 103 L mol-1 cm-1. The method allows a reliable determination of fluoride in the range 0.3─3.0 mg L-1 which is compatible to WHO limit value of 1.5 mg L-1. The sensitivity, detection limit, quantitation limit, and correlation coefficient for the method were found to be 0.211 μg mL-1, 0.1 mg L-1, 0.3 mg L-1, and 0.9914 respectively. The percentage recovery of 1.5 mg L-1 fluoride is 101.3.

Field determination of fluoride in drinking water using a polymeric aluminium complex of 5-(2-carboxyphenylazo)-8-hydroxyquinoline impregnated paper

A simple field method which allows the determination of fluoride in drinking water with a small handheld instrument called Arsenator was developed. Arsenator is a commercially available instrument which was used successfully for reliable determination of arsenic. In the proposed method the functionality of the Arsenator which is based on a photometric measurement of a spot on the reagent paper is expanded to analyse fluoride. A polymeric aluminium complex of 5-(2-carboxyphenylazo)-8-hydroxyquinoline (LH2) has been prepared as a new specific reagent for fluoride. Job's method of continuous variation was adopted for the determination of the composition of the coloured complex, which was further characterized by UV-VIS spectroscopic studies. The molar absorptivity of the complex formation is 8.48 × 103 L mol−1 cm−1 at 410 nm. The coloured complex reacts with fluoride on an impregnated paper where its colour changes are dependent on the concentration of fluoride in water samples. The change in the colour was measured using the Arsenator. The method allows a reliable determination of fluoride in the range 0.3 to 2.0 mg L−1. Further spectophotometric determinations of fluoride in drinking water were also studied. The determination is based on the reaction of aluminium complex with fluoride in the examined samples. Beer's law is obeyed in the range 0.3 to 2.0 mg L−1 of fluoride at 495 nm. Sensitivity, detection limit and quantitation limit of the method were found to be 0.251 ± 0.007 µg−1 mL, 0.1 mg L−1 and 0.3 mg L−1, respectively. The optimum reaction conditions and other analytical conditions were evaluated. The effect of interfering ions on the determination is described. There is no interference by nitrate or chloride. Sulphate interfered only at high concentrations which are not expected in drinking water.

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.

Fluoride pollution in soils and waters of Koohbanan region, southeastern Iran

Dental fluorosis occurs because of fluoride over-absorption during tooth calcification and maturation. We studied fluoride concentration in water and soil samples of the Koohbanan region in Kerman province of southeastern Iran and the effects of calcium chloride and gypsum treatments in decreasing the amount of fluoride in water samples of this region. The results indicate that the high amount of fluoride in the water samples of Koohbanan region is not in agreement with the recommended amount of fluoride concentration for drinking water by World Health Organization (that is 1–1/5 mg/l). Applying calcium chloride and gypsum treatments decreased the amount of fluoride in the water samples showing that utilizing calcium chloride (6 mg/l) or gypsum (12 mg/l) can lower the fluoride concentration in the water samples of Koohbanan, and thus solve the observed dental fluorosis problem.

Solid phase extraction–spectrophotometric determination of fluoride in water samples using magnetic iron oxide nanoparticles

A new, sensitive, fast and simple method using magnetic iron oxide nanoparticles (MIONs), as an adsorbent has been developed for extraction, preconcentration and determination of traces of fluoride ions. The determination method is based on the discoloration of Fe(III)–SCN complex with extracted fluoride ions which was subsequently monitored spectrophotometrically at λ max = 458 nm. Various parameters affecting the adsorption of fluoride by the MIONs have been investigated, such as pH of the solution, type, volume and concentration of desorbing reagent, amount of adsorbent and interference effects. A linear response for the determination of fluoride was achieved in the concentration range of 0.040–1.250 μg mL −1. The limit of detection (LOD) and limit of quantification (LOQ) for fluoride based on 3 times and 10 times the standard deviation of the blank (3S b, 10S b) were 0.015 and 0.042 μg mL −1 ( n = 20) for fluoride ion, respectively. A preconcentration factor of 50 was achieved in this method. The proposed procedure has been applied for determination of fluoride concentration in various water samples. The results obtained from this method were successfully compared with those provided by standard SPADNS method.

Effect of fluoride intoxication on the levels of intestinal antioxidants studied in rats

High concentration of fluorine is noxious to the health of humans and animals. Analysis of fluoride in water samples meant for human consumption in the Vellore District of Tamil Nadu, India, revealed its presence above the permissible limit (4.56 ppm). The present study was aimed to investigate the toxic effects of oral administration of the water sample that contains the highest fluoride content on the status of pathophysiological parameters and lipid peroxidation in experimental rats. A positive control group orally treated with 4.5 ppm of fluoride was also included in the study. The assay of pathophysiological enzymes and histological observations made on the stomach and intestinal tissue have revealed the toxic effects of fluoride intoxication. The observed increase in the levels of thiobarbituric acid reactive substances (TBARS) both in plasma and in intestinal epithelium, with a concomitant decrease in both enzymatic and nonenzymatic antioxidants in the plasma of experimental rats, revealed that the altered antioxidant status during fluoride intoxication may be due to increased free radical generation.

Availability of fluoride from meals given to kindergarten children in Brazil

The aim of this study was to evaluate the amount of fluoride supplied daily in the meals given in 44 public kindergarten schools in Bauru, Brazil. In addition, the fluoride concentration of water supplies and its impact on the amount of fluoride found in the meal samples were also investigated. Meal samples and water were collected during 2 weeks (10 working days) in public kindergarten schools. Samples of meals were homogenized with known volumes of deionized water. Fluoride present in meal samples was analyzed with the ion-specific electrode (Orion 9609), after hexamethyldisilazane-facilitated diffusion. Fluoride in water samples was analyzed with the same electrode, after buffering with TISAB II. All the analyses were made in duplicate. Fluoride analyzed (mean+/-SD) was 0.50+/-0.20 microg/ml, ranging from nondetectable to 1.42 microg/ml for water samples (n=424) and 0.067+/-0.059 mg, ranging from 0.007 to 0.580 mg for meal samples (n=431). A weak but significant correlation was observed between the amount of fluoride in meals and fluoride concentration in water supplies (r=0.139, P=0.0042). Despite the seemingly small role played by school meals in the total daily fluoride intake, they can contribute to the total fluoride intake of children on a chronic basis, when in association with other fluoride products. Additionally, the impact of fluoridated public water supply on the final fluoride concentration of the school meals analyzed may be regarded as low.

Fluorimetric determination of fluoride in a flow assembly integrated on-line to an open/closed FIA system to remove interference by solid phase extraction

A simple flow injection fluorimetric method for fluoride determination is proposed. The method is based on the enhanced fluorescence of quercitin–Zr(IV) complex when fluoride ion is present in the sample. An open/closed FIA manifold with a mini-column of Dowex 50W X8 resin was used to remove the most important interference (aluminum). The two FIA assemblies were integrated on-line to automate the pretreatment of the water sample and fluoride determination. The calibration graph was linear over the range 0.1–3.0 μg ml −1 of fluoride with a correlation coefficient of 0.999 and LOD 0.06 μg ml −1. The relative standard deviation was 2.5% and the sample throughput was 52 h −1 without pretreatment and 10 h −1 with pretreatment of the sample. The method was applied to the determination of fluoride in water samples.

Gas diffusion with preconcentration for the determination of fluoride in water samples by flow injection

The preconcentration of fluoride is achieved on-line by converting it to trimethylsilane which then diffuses through a gas permeable membrane to be absorbed in a stationary sodium hydroxide acceptor stream. This stream is enclosed in the sample loop of an injection valve and after preconcentration, the fluoride sample is flushed into a flow injection manifold for spectrophotometric analysis by the zirconium/alizarin S procedure at 520 nm. The method is suitable for fluoride analysis in the range 0.1–10 mg/l at a sampling rate of 17/hr. Phosphate does not interfere and aluminium and iron can be tolerated at 200 and 500 times the fluoride concentration, respectively. The LOD was calculated to be 0.055 mg/l and LOQ was found to be 0.18 mg/l.

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.

Determination of fluoride in water samples by substoichiometric extraction with trimethylchlorosilane

The determination of fluoride in aqueous solutions by substoichiometric extraction was performed using a carrier-free spike of18F (T=110 m). The principle, the procedure of the determination and the results of some tap water and urine analysis are given.