Fluoride Ion-selective Electrode Research Articles

Selective fluoride removal in capacitive deionization by reduced graphene oxide/hydroxyapatite composite electrode

Capacitive deionization (CDI) is an emerging desalination technology with an environmental-friendly operation and energy-efficient properties. However, activated carbon (AC) used for CDI electrode does not have a significant preference toward anions, leading to unnecessary energy consumption for treating fluoridated water. Hence, we achieved selective fluoride removal in CDI system using a reduced graphene oxide/hydroxyapatite composite (rGO/HA), a novel fluoride selective electrode material. The results showed that the rGO/HA electrode has 4.9 times higher fluoride removal capacity than the AC electrode from a ternary solution consisting of fluoride, chloride, and nitrate ions. The fluoride removal capacity increased when the adequate voltage was applied. Furthermore, the rGO/HA electrode exhibited stability and reusability without significant capacity loss even after 50-cycle operation, maintaining about 0.21 mmol g−1 of fluoride removal capacity and approximately 96% of regeneration efficiency. Thus, this study suggests a novel electrode material for effective and selective fluoride removal in the CDI system.

Prevalence of dental and skeletal fluorosis in relation with the fluoride levels in drinking water among the primary school children at Laxmisagar Grampanchayat of Bankura District, West Bengal India

To estimate the prevalence of dental and skeletal fluorosis in relation with different fluoride levels in drinking water among school going children aged 6-12 years. The cross sectional study was conducted in the six primary schools of Lakshmisagar Grampanchayat, Bankura District, West Bengal, India. Dental fluorosis was recorded using Dean's index. The drinking water samples were collected in polyethylene bottles and the fluoride content of these samples was determined by fluoride ion selective electrode method using Orion microprocessor analyser. The overall prevalence of dental and skeletal fluorosis among the school students of this study area was 78.47% and 13.87% respectively. The study noted that the maximum fluoride level in the drinking water of the six schools were 9.15, 3.46, 3.46, 3.46, 3.28, and 2.11 ppm respectively though the prevalence of dental fluorosis was noted among the students of this region were 100.00%, 76.92%, 78.85%, 42.86%, 91.30% and 94.74% respectively. This study found that the fluorosis level in drinking water was not the single most factors for determining the fluorosis but there might be some other factors associated with causation of fluorosis and these factors also modulate the severity of the fluorosis. Nutrition is the most important factors to reduce the fluoride level from the human body. Keywords: Fluorosis, Fluoride, Bankura district, Prevalence.

Determination of fluoride in tea leaves and tea infusions by ion selective electrode

A fluoride ion selective electrode method for the determination of fluoride contents in tea leaves and tea infusions was set up. Using commercial timothy grass powder and tea leaf powder as standard materials, this method demonstrated linearity between 0.02 and 2.00 mg/L of fluoride with R2 greater than 0.999. Both materials had coefficient of variations (CV, %) less than 3%, indicating good reproducibility in the determinations. The recovery tests of tea infusions spiked with different amounts of sodium fluoride demonstrated 94-107% of recovery with CV less than 1.2%, indicating that the method is very accurate. With 1% of tea leaves to boiling water ratio, up to 63-78% of fluoride in tea leaves could be released into tea infusion by repeated infusions and 82-83% by continuous infusion. By this method, total fluoride contents of 12 brands of tea leaves purchased from Nantou County were determined to be 100-451 mg/kg dry weight, and those of their infusions in boiling water for a 5-min period were determined to be 0.39-1.21 mg/L. Assuming that daily tea infusions drinking for an adult is 2 L, fluoride intake from tea infusions of these tea leaves is far below the daily fluoride tolerable upper limit 10 mg.

Nanometer-Thick Ion-Selective Polyelectrolyte Multilayer Coatings to Inhibit the Disintegration of Inorganic Upconverting Nanoparticles

Protective and ion selective polyelectrolyte multilayer coatings from poly(sodium 4-styrenesulfonate) and poly(diallyldimethylammonium chloride) were manufactured on the NaYF4:Yb3+,Er3+ upconverting nanoparticle surface. The ion selective coatings would be effective in hindering the disintegration of inorganic nanoparticle in an aqueous environment used in various applications such as in vitro assays and biomedical imaging. The disintegration is prominent especially in detrimental phosphate-based buffers. The effect of the used counteranion on the multilayer formation and the luminescent properties of the coated materials is discussed. The multilayer coating was confirmed with Fourier transform infrared spectroscopy, thermal analysis, and transmission electron microscopy. The behavior of the coated nanoparticles in aqueous environment was monitored by using fluoride ion selective electrode. We observed that the ion selective coatings prepared using fluoride or chloride as a counteranion were the most effective in slowing the disintegration of the nanoparticles. The deceleration in the disintegration process was observed also in phosphate-based buffer which emphasizes the ion selective properties of the multilayer coating. The upconversion luminescence measurements of the coated nanoparticles showed that coatings manufactured with bromide counteranion were most efficient in shielding the upconversion luminescence in solid state.

Comparison of Fluoride Ion Release from Fluoride Gel in Various Solvents.

ObjectiveThe aim of this study was to determine the concentration of fluoride ions present in various solvent solutions and compare it to the label amount of fluoride concentration.Material and methodsThe gel containing amine fluoride and sodium fluoride was compared to gel containing sodium fluoride only. The solvents used in this study were distilled water, redistilled water, tap water, 0.9% sodium chloride solution and the artificial saliva. The amount of fluoride ion (F-) was determined by the use of fluoride ion-selective electrode. The ANOVA and the Post hoc Tukey’s test were used. The significance level was α = 5%.ResultsThe differences between F- ion release in various solvents were statistically significant (p < 0.05). The F- ion concentrations measured in both gels’ redistilled water solutions were higher than the label concentration. There was a significant difference in fluoride ion release in sodium fluoride only gel solutions. Fluoride ion release was significantly different in combined fluoride gel solutions.ConclusionsAmine fluorides do not interact with other ions present in the solution, whereas F- ion release from sodium fluoride alters when other ions are dissolved in the same solution. Amine fluorides deliver F- ions for caries prevention more efficiently.

OPAA/fluoride biosensor chip towards field detection of G-type nerve agents

Sensor technology, particularly disposable, field-deployable devices offer considerable promise for addressing major security demands, in general, and in particular the urgent needs for selective and rapid field detection of highly toxic G-type organophosphate (OP) nerve agents. Herein, we report on the first example of a disposable electrochemical biosensor chip for decentralized field detection of diisopropyl fluorophosphate (DFP), as the simulant compound of G-type nerve agents (e.g., Sarin and Soman), based on the integration of an all-solid-state fluoride potentiometric transducer with the enzyme organophosphorus acid anhydrolase (OPAA) in connection to a hand-held potentiometric analyzer. Such solid-contact fluoride ion-selective electrodes were realized by comparing different fluoride ionophores to select the bis(fluorodioctylstannyl)methane molecule, along with systematic optimization of the experimental parameters. This first solid-contact fluoride detection chip displayed a favorable analytical performance, with near-Nernstian behavior at neutral pH in different buffers, high selectivity against various anions along with excellent reproducibility. Combining such desirable merits of the new fluoride sensor with the selective biocatalytic hydrolysis via an immobilized OPAA, to break the PF bond of G-type neurotoxins and release detectable fluoride ions, thereby enabled an attractive analytical performance. Both the fluoride and the nerve-agent recognition layers have thus been systematically optimized. The resulting biosensor chip thus displays a fast, sensitive and selective response towards DFP (including efficient discrimination against OP pesticides), along with a wide dynamic range of 250–3000 μM. Key challenges towards developing the nerve-agent detection chip were carefully addressed, including the pH incompatibility of the enzymatic and detection processes. By providing effective discrimination against common OP pesticides and minimizing related false alarms, the resultant disposable potentiometric biochip platform is expected to provide an instantaneous reliable warning of chemical attack and exposure towards a timely countermeasure action, and hence, would dramatically advance the protection of our military personnel.

Radionuclide activity concentration in soil, granites and water in a fluorosis endemic area of India: An oral health perspective

BackgroundThe idea that hilly areas have a high background radiation which in turn is linked to dental fluorosis is widely held by many in India. There is little evidence to confirm this. ObjectiveThe study aimed to investigate the level of environmental radionuclide in order to determine any interrelationship between radionuclide and dental fluorosis in Pavagada, a fluorosis endemic area of Karnataka, India. MethodsGamma radionuclides (Th232, Ra226 and K40) were determined by high purity germanium (HPGe) gamma-ray spectrometer (Bq Kg-1) using a 50% relative efficiency p-type broad energy HPGe detector. Fluoride was estimated using fluoride Ion-selective electrode (ISE). Fluorosis was assessed using WHO diagnostic criteria. ResultsThe average mean +_SD activity concentration in soil for K40 was detected between 416.6 ± 9.3 and 769.1 ± 15.0. Th232 was estimated between 13.6 ± 0.6 and 57.6 ± 1.3; and Ra226 was found between 6.4 ± 0.4 and 21.6 ± 0.7. Similarly, the mean activity concentration detected (Bq kg-1) in granite for K40 ranged between 259.8 ± 6.9 and 1608.5 ± 26.9. The activity concentration of Th232 ranged between 26.4 ± 0.8 and 57.6 ± 1.3: and that of Ra226 was between 6.6 ± 0.3 and 21.6 ± 07. Drinking water contains 2.98 ppm of fluoride. Dental fluorosis was diagnosed as mild to moderate. ConclusionThe radionuclide activity in water, soil and granites were below the detection limit. Hence, the study revealed no association of fluorosis and radionuclide level in Pavagada, Karnataka, India. This helps resolve an ambiguity.

Fluoride Release from Composite Resin in Different Media

Objective: The present study aimed to measure the released from composite resins stored in different beverages. Materials and Methods: Three composite resins (Te-Econom, Tetric ceram, and VOCO) were used. Twenty specimens for each composite resin were prepared according to the manufacturer instructions, and were divided into four groups (The first group were stowed in deionized water, the second group were stowed in orange juice, the third group were stowed in Pepsi Cola while the last group were stowed in coffee without sugure). The storage solutions were replaced after 7, 15 and 30 days and release (FR) at the end of each storage period was measured by fluoride ion selective electrode. Results: One way analysis and Duncan test were used to statistically analyze the data. The amount of FR from the tested materials was significantly higher in orange juice (at day 15) than the amount of released in coffee and Pepsi Cola. The amount of released from the tested materials was significantly higher in Pepsi cola (at day 7) than the amount of released in orange and Pepsi cola. Conclusion: The ability of restorative dental materials to slowly release ions may provide a positive advantage in terms of recurrent caries inhibition.

Comparison of oral health indicators between two places of endemic dental fluorosis in Jordan

IntroductionExcessive fluoride intake during tooth development causes dental fluorosis. AimThis study aimed to (1) determine the prevalence of dental fluorosis in association with fluoride concentrations in drinking water, (2) explore the effects of altitude on the severity of fluorosis in two towns with high fluoride levels in the drinking water, and (3) assess decayed, missing, and filled teeth (DMFT) and oral hygiene practices among participants. Material and methodsThe sample consisted of 100 and 141 schoolchildren, aged 15.3 ± 1.4 and 16.1 ± 1.3 years, living in Ruwaished and Kuraymah, respectively. Oral examinations were carried out, and dental fluorosis was assessed using the Dean’s index. The DMFT index was also used for assessment. Samples of drinking water were analyzed using a fluoride-ion selective electrode. SPSS was used to analyze the data. ResultsTwo-thirds (68.8%) of adults from Kuraymah had moderate to severe fluorosis, with only 7% being unaffected. In Ruwaished, 50% of the sample had severe fluorosis, 22% showed moderate fluorosis, and none were unaffected. The average DMFT scores were 3.18 ± 1.81 and 3.81 ± 1.41 for Kuraymah and Ruwaished, respectively. In both towns, males had significantly higher caries scores than females. Oral hygiene was poor, as 64% and 57% of the participants from Kuraymah and Ruwaished, respectively, did not brush their teeth. A significant correlation was found between poor oral hygiene and increased DMFT scores. ConclusionsThis study concluded that higher fluorosis incidence and severity were present in the higher-altitude location (Ruwaished). Moreover, this study also indicated that fluorosed teeth are not immune to caries, and the preventive management of dental fluorosis should be directed to de-fluoridation of drinking water in endemic areas.

Surprisingly high fluorine content in some exotic superfoods

Recent years have seen soaring interest in exotic superfoods, which are believed to have extraordinary health benefits. The purpose of the study was to broaden the current knowledge on exotic superfoods and to analyse them for fluorine (F)11In this paper, “fluorine” is used to denote the element in any of its forms and “fluoride” is used to denote the inorganic compound and the fluoride ion F−. since excessive intake during prolonged periods of time can cause adverse effects. The F content was determined in 18 plant-based exotic superfoods available on Slovenian market by fluoride ion selective electrode after prior total decomposition by alkaline carbonate fusion. In 8 of the analysed samples, the F content was surprisingly high in comparison to F content in commonly consumed foods (<3 μg/g). The highest F content was found in matcha (373 μg/g), followed by gotu kola (111 μg/g) and gingko biloba (91.0 μg/g). The F content in tulsi, neem, brahmi, gynostemma and moringa was lower and ranged between 16.4–68.8 μg/g. Despite high F content, these superfoods do not pose a risk to human health in non-fluoridated water areas, because they are usually consumed in low quantities. However, in fluoridated water areas (e.g. some parts of Ireland, United Kingdom, United States, Canada) or in areas with high natural fluoride concentration in drinking water, superfoods should be consumed with caution, since the intake of F can with simultaneous consumption of superfoods and tea on a normal diet easily exceed the adequate intake or even reach the upper limit of fluorine. The F content in these 8 superfoods was also surprisingly high in comparison to the usual F content in most plant species (<10 μg/g). The high F content in matcha is understandable since it is made of Camellia sinensis L. leaves, but the high F content in other superfoods is worrisome because the reason for such high F content is unknown and it is possible that these superfoods are contaminated with fluoride due to industrial or agricultural activities.

Fluoride exposure and CALCA methylation is associated with the bone mineral density of Chinese women

Excessive exposure to fluoride has been reported to affect bone mineral density (BMD). CALCA expression plays a critical part in bone formation. However, the role of CALCA in the association between fluoride and BMD is not known. We conducted a cross-sectional study and recruited 722 women in rural areas of Henan Province, China, to assess the relationship between fluoride exposure, CALCA methylation, and BMD. Urinary levels of fluoride, CALCA methylation, and BMD were measured by a fluoride ion-selective electrode, standalone ultrasound bone densitometer, and quantitative methylation-specific polymerases chain reaction, respectively. The association among fluoride exposure, CALCA methylation, and BMD was age-specific. Specifically, BMD was negatively correlated with methylation (β: −0.008; 95% CI: −0.016, 0.000) and fluoride exposure (β: −0.063; 95% CI: −0.129, −0.002) in women over 45 years and 50–54 years of age, respectively, whereas methylation was positively correlated with fluoride exposure (β: 4.953; 95% CI: 1.162, 8.743) in women aged 40–44 years. Besides, increased BMD in women aged 45–49 years induced by the interactive effect of the highest methylation of CALCA exon 1 (tertile 3) and fluoride exposure was observed (P for interaction < 0.05). Our findings suggest an age-specific association between exposure to excessive fluoride, CALCA methylation, and BMD in a rural population of women in China. Notably, the susceptibility of BMD to fluoride exposure may be modified by CALCA methylation.

Chemically Soluble Fluoride in Na2FPO3/CaCO3-Based Toothpaste as an Indicator of Fluoride Bioavailability in Saliva during and after Toothbrushing

The relationship between the concentration of chemically soluble fluoride found in toothpaste and that present in saliva, during and after brushing, was evaluated as an indicator of potentially bioavailable fluoride in toothpaste. Ten adult participants brushed their teeth with the assigned toothpastes: group I: fresh sample of a fluoride toothpaste: Na₂FPO₃/CaCO₃, 1,378 µg F/g of total soluble fluoride (TSF); groups II–IV: aged samples of toothpaste presenting TSF concentrations of 1,160, 900, and 597 µg F/g, respectively; group V: non-F placebo toothpaste. The volunteers brushed their teeth for 1 min with 0.7 g of the toothpaste, all toothbrushing residues (TR) produced were collected, the mouth was rinsed with water, and saliva samples were collected up to 120 min. Total fluoride (TF) and TSF concentrations were determined in TR and in saliva samples using a fluoride ion-selective electrode. TSF concentration (µg F/mL) in TR was determined as an indicator of fluoride bioavailability during toothbrushing and the areas under curves of saliva fluoride concentration versus time (area under the curve, AUC = µg F/mL × min) were calculated as an indicator of fluoride bioavailability after toothbrushing. A significant correlation was found between the TSF concentrations in the toothpastes and the variables TR (r = 0.850; p = 0.0001) and AUC (r = 0.445; p = 0.004). For TF no significant correlation was found for TR (r = –0.099; p = 0.542) and AUC (r = –0.018; p = 0.912). The findings suggest that TSF concentration chemically found in Na₂FPO₃/CaCO₃-based toothpaste could estimate how much fluoride would be bioavailable in saliva when the teeth are brushed.

Potential of bacterial consortia obtained from different environments for bioremediation of paroxetine and bezafibrate

This work aimed to isolate and identify the culturable bacterial strains from five enriched cultures and investigate the capability of these strains to biodegrade paroxetine (Prx) or bezafibrate (Bzf), when assembled into consortia. Bacterial strains were isolated from cultures enriched with Prx and Bzf using, as microbial inocula, an estuarine sediment and activated sludge from an associated wastewater treatment plant. All the isolated strains were identified through 16S rRNA gene sequencing. Pharmaceutical compounds were analyzed by HPLC-DAD (diode array detector). Fluoride release was analyzed using a fluoride ion-selective electrode to evaluate the extent of paroxetine defluorination. High removal efficiency of pharmaceuticals (>97 %) was observed for three of the five assembled consortia. A total of 28 bacterial strains were isolated from an activated sludge enrichment and 20 bacterial strains were isolated from an estuarine sediment enrichment. The genera Pseudomonas and Acinetobacter were the most dominant in the consortia derived from activated sludge, while the genus Pseudomonas was dominant in the consortia derived from estuarine sediment. This work highlights the potential of native bacterial consortia obtained from different environmental sources to biodegrade Prx or Bzf, and unveils the taxonomic diversity associated to the biodegradation of these compounds. These consortia may be considered in the future for the development of new bioremediation tools for environmental restoration.

Fluoride‐Selective Electrode as a Tool to Evaluate the Degradation of PFAS in Groundwater: A Bench‐Scale Investigation

AbstractFluoride (F−) concentration in groundwater can be used as an independent measure of the degradation of per‐ and polyfluoroalkyl substances (PFAS) at contaminated sites. This study assessed the impact of the groundwater matrix, oxidizing reagents, quenching agent, and sample handling procedures (filtration) on determinations of F−. F− was quantified using a fluoride‐selective electrode (FSE) using matrix spike recovery (acceptable range 75 to 125%) and electrode slope performance (ideal range −54 to −60 mV). For the unaltered aqueous matrices considered (ultrapure water, ultrapure water with sodium chloride, and simulated groundwater), matrix spike recoveries were greater than 93% and acceptable electrode slopes (−59.5 ± 0.2 mV) were obtained. Matrix spike recoveries and electrode slopes when persulfate or permanganate was added were 87 and 93%, and −58.4 ± 1.3 and −47.3 ± 2.2 mV, respectively. Therefore, quantifying F− in matrices containing permanganate should involve use of either a matrix‐matched calibration curve or the method of standard additions due to the low electrode slope. The addition of ascorbic acid as a quenching agent resulted in a decrease in matrix spike recoveries to &lt;74% and suggests alternate quenching procedures should be used if an FSE is employed to measure F−. Removal of sediments by filtration prior to the addition of the fluoride spike led to improved matrix spike recoveries (&gt;96%), which were otherwise underestimated using the FSE in the presence of sediments. While the FSE may be a quick and portable tool, its significant limitations need to be fully understood before it can be used to quantify the production of F− resulting from the potential degradation of PFAS at field sites.

Removal of fluoride from aqueous solution by porous Vaterite calcium carbonate nanoparticles

This study is based on a simple, low-cost and a novel approach towards the removal of excess fluoride ions from aqueous solution by absorbing fluoride on porous vaterite calcium carbonate nanoparticles (PVCCNPs) synthesised using ethylene glycol-water soft template method. SEM images clearly show the porous nature of aggregated nanoparticles present in the dry powder. Physicochemical properties of synthesised PVCCNP and fluoride on PVCCNP was characterised further by FTIR, XRD, XRF, EDX, and TGA-DTG. Fluoride removal by PVCCNPs from 100.00 ml of 10.0 mg l−1 NaF solution with 0.500 g of PVCCNPs, determined using a fluoride ion-selective electrode, indicates that around 90% removal is achieved within 1 h thus reducing the level to desired 1 ppm. The pseudo-second order kinetic model has a better fit to describe the adsorption of fluoride on PVCCNP than pseudo-first order model. The Langmuir isotherm model is more appropriate to describe the equilibrium behaviour of the adsorption process, than the Freundlich model. Given that the value of n (Freundlich constant) is greater than 1 (3.07) and RL value is in the range of 0 < RL <1 (0.014–0.024) implies that the adsorption process is spontaneous and fluoride ions are favourably adsorbed on PVCCNPs. Langmuir model shows that the maximum adsorption capacity of fluoride is 1.956 mg g−1. Excess fluoride in drinking waters causes several severe ill-health effects and filter media based on these nanoparticles can be used to remove fluoride down to safe and required levels to tackle these health problems. As such, PVCCNPs-based filter can be designed to remove fluoride in drinking waters. This may be a way for controlling fluorosis and many other diseases associated with excess fluoride present in drinking waters.

Direct Potentiometric Sensing of Anion Concentration (Not Activity).

Potentiometric probes used in direct potentiometry are attractive sensing tools. They give information on ion activities, which is often uniquely useful. If, instead, concentrations are desired as sensor output, the ionic strength of the sample must be precisely known, which is often not possible. Here, for the first time, direct potentiometry can be made to report concentrations, rather than activities. It is demonstrated for the detection of monovalent anionic species by using a self-referencing Ag/AgI pulstrode as the reference element instead of a traditional reference electrode. This reference pulstrode releases a discrete quantity of iodide ions from the electrode and the resulting reference potential varies with the activity coefficient of iodide. The effects of activity coefficient on the indicator and reference electrode are therefore compensated and the observed cell potential may now be described in a Nernstian manner against anion concentration, rather than activity. Theoretical simulations and experimental results support the validity of this approach. For most monovalent anions of practical relevance, the potential difference between this approach and from a traditional activity coefficient calculation is less than 0.5 mV. The concept is validated with an all-solid-state nitrate sensor as well as a commercial fluoride-selective electrode, giving Nernstian responses in different ionic strength backgrounds against concentration without the need for correcting activity coefficients or liquid junction potentials.

Defluoridation of drinking water using coalesced and un-coalesced mica

This is a sorption study that focused on the use of mica clay mineral grouped into mica untreated, activated mica at 800 °C, mica impregnated separately with iron and aluminium for defluoridation of water. In this study, characterization of adsorbent was done by using XRF and XRD and quantification of fluoride by using fluoride ion selective electrode. Characterization of adsorbent showed the presence of SiO2, CaO, P2O5, Fe2O3 and Al2O3 in the adsorbent. XRD exhibited higher composition of illite, calcite, quartz and albite. Batch experiments were conducted by using a homogeneous mixture of water having 16 mg/L of fluoride. The removal efficiencies of mica alone, activated mica at 800 °C, mica impregnated with iron and mica impregnated with aluminium were found to be 76.02%, 90.21%, 94.40% and 96.88%, respectively. Activated mica and coalesced mica are better adsorbents than mica alone. The optimized pHs were 7.3, 4.4, 7.5, doses of 10, 9 and 8 g, contact time of 40, 35 and 30 min for activated mica, mica impregnated with iron and mica impregnated with aluminium, respectively. The adsorption process obeyed Freundlich model for mica impregnated with aluminium indicating monolayer mechanism, whereas activated mica and mica impregnated with iron agreed with both Freundlich and Langmuir models indicating both monolayer homogeneous and heterogeneous surface conditions. From the kinetic perspective, the fluoride adsorptive reaction followed the pseudo-second-order model. Therefore, activated and modified mica are alternative adsorbents for defluoridation of water.

Fluoride levels in supply water from a volcanic area in the Macaronesia region.

Fluoride is a widely distributed ion in the environment and, consequently, in water as well. High levels of fluoride in waters can be found in the Canary Islands because of their volcanic origin. Due to the risk and detrimental effects associated with a high fluoride intake, the content of this ion has been potentiometrically determined in 256 supply water samples from the islands of Tenerife, El Hierro, and La Palma, using a fluoride selective ion electrode. Fluoride mean concentration found on Tenerife is 4.22mg/L, exceeding the parametric value of 1.5mg/L set out in Spanish legislation. The consumption of 2L of water from the studied municipalities of Tenerife would mean there is an excessive fluoride intake. The consumption of this water poses a serious risk to health. It is necessary to take action aimed at reducing the level of fluoride in the north of the island of Tenerife.

Determination of Fluoride in Various Samples Using a Fluoride Selective Electrode

Fluoride is widespread in the environment, water, air, vegetation and Earth’s crust which can entre ground and surface water by natural process. Fluoride in minute quantities is essential component for human health and help in normal mineralization of bone and formation of dental enamel. The determination of fluoride in some species was performed by using fluoride ion-selective electrode by direct measurement and standard addition method. The concentration of fluoride ion was determined in drinking water (from different place at Kathmandu), toothpaste, various brand of tea and coffees. The range of fluoride concentration in water sample was 0.16 to 0.39 mg/l, tea and coffee samples were 0.011 to 0.084 mg/l and its value of toothpaste was 0.026 to 0.75 mg/l. The concentration of fluoride ion obtain from different sample was compared with the legitimate value given by the world health organization.

The effect of ionizing radiation on properties of fluoride-releasing restorative materials

The purpose of this study was to evaluate the effect of ionizing radiation from high energy X-ray on fluoride release, surface roughness, flexural strength, and surface chemical composition of the materials. The study groups comprised five different restorative materials: Beautifil II, GCP Glass Fill, Amalgomer CR, Zirconomer, and Fuji IX GP. Twenty disk-shaped specimens (8x2 mm) for fluoride release and 20 bar-shaped specimens (25 x 2x 2 mm) for flexural strength were prepared from each material. Each material group was divided into two subgroups: irradiated (IR) and non-irradiated (Non-IR). The specimens from IR groups were irradiated with 1.8 Gy/day for 39 days (total IR = 70.2 Gy). The amount of fluoride released into deionized water was measured using a fluoride ion-selective electrode and ion analyzer after 24 hours and on days 2, 3, 7, 15, 21, 28, 35, and 39 (n = 10). The flexural strength was evaluated using the three-point bending test (n = 10). After the period of measurement of fluoride release, seven specimens (n = 7) from each group were randomly selected to evaluate surface roughness using AFM and one specimen was randomly selected for the SEM and EDS analyses. Data were analyzed with two-way ANOVA and Tukey tests (p = 0.05). The irradiation significantly increased fluoride release and surface roughness for Amalgomer CR and Zirconomer groups (p < 0.05). No significant change in flexural strength of the materials was observed after irradiation (p > 0.05). The ionizing radiation altered the amount of fluoride release and surface roughness of only Amalgomer CR and Zirconomer. The effect could be related to the chemical compositions of materials.