Potentiometric Determination of Fluoride Concentration in Beers

Soft Drinks as a Dietary Source of Fluoride Exposure

High fluoride exposures can lead to adverse effects such as dental and bone fluorosis, as well as endocrine and cognitive developmental problems. Water is the main dietary source of this ion, although significant concentrations have also been detected in other beverages widely consumed by the population such as soft drinks. A total of 200 soft drink samples (60 flavoured, 70 extracts, 60 fruit juice and 10 soft drinks) were analysed by fluoride ion selective potentiometry. A consumption of 330 mL was estimated for exposure assessment and subsequent F-risk assessment by soft drink consumption. The highest average concentration was found in extract soft drinks (2.45 ± 1.15 mg/L), followed by flavoured (1.71 ± 2.29 mg/L) and carbonated soft drinks (1.38 ± 0.40 mg/L), while the lowest was found in fruit juice soft drinks (1.09 ± 0.62 mg/L). The flavours with the highest concentration were tea-melon and tea-passion fruit with 3.66 ± 0.40 and 3.17 ± 0.56 mg/L respectively and the lowest was lemon flavour with 0.69 mg/L. The contribution of these beverages, considering the UL (Upper level) reference values set by EFSA (European Food Safety Authority) are between 3.28-41.78%, depending on age group and sex.

Layered double hydroxide nanoparticles for a smartphone digital image colorimetry-based determination of fluoride ions in water, milk and dental products

A novel smartphone digital image colorimetry-based approach was developed for fluoride ion determination, using layered double hydroxide (LDH) nanoparticles (Mg2Al(OH)7) as sorbents for analyte preconcentration and as a source of a central metal ion for a colored complex formation. A cotton rotating disk provided effective retention of the LDH nanoparticles during solid-phase microextraction and elution, excluding time-consuming centrifugation process. In the proposed procedure, the nanoparticles acted as aluminum ion source for alizarin complexone-Al3+-F- complex formation. An image of Eppendorf tube, containing the colored complex solution was obtained by a smartphone and converted, using the RGB model for fluoride ion determination. The procedure had a linear range of 0.20-20 mg L-1 with a limit of detection of 0.06 mg L-1. The developed procedure provided effective fluoride separation from various matrices for its determination by a smartphone without additional sample pretreatment.

Potentiometric Determination of Free Fluoride Content in Wines from Dalmatia Region (Croatia)—A Comparative Study of Direct Potentiometry and Standard Addition Method

The aim of this study was to investigate 30 different types of Dalmatian wines as a potential source of fluoride. A fluoride ion selective electrode was used to measure the fluoride concentration in each sample. The direct potentiometric method and the standard addition method were evaluated, the latter being suggested as more accurate and precise. Measurements were performed in two buffers, acetate buffer and total ionic strength adjustment buffer (TISAB), to compare their influence on fluoride determination. The obtained results show that TISAB is a better choice than acetate buffer as a medium for fluoride determination. According to the proposed method, mass concentrations of fluoride of 0.19 and 0.18 mg/L were found in the studied red and white wines, with standard deviations of 0.04 and 0.03 mg/L, respectively. All determined fluorine levels in the tested wines were within the recommended limits and do not pose a risk to human health. No significant difference was found between the fluorine content in white and red wines, but there was a difference depending on the place of origin of the wine. The measured pH values for all the wines studied (except one sample) are very similar and show no significant correlation with the fluoride content.

Fluoride Exposure from Soybean Beverage Consumption: A Toxic Risk Assessment

The consumption of vegetable milk as a substitute for cow's milk has increased in recent years. Of all the vegetable beverages on the market, soy is the most widely consumed. Soy is exposed to contamination by different chemical elements during harvesting. In this study, the concentration of fluoride in soy beverages was analyzed. Fluoride is an element that in high concentrations can be toxic, causing dental and bone fluorosis. The aims of the study were (i) to analyze the fluoride concentration in 30 samples in the most popular brands (A-Brand, B-Brand, C-Brand) of soybean beverages by a fluoride ion selective potentiometer and (ii) to evaluate the toxicological risk derived from its consumption. The fluoride concentrations were 15.5 mg/L (A-Brand), 11.3 mg/L (B-Brand) and 8.5 mg/L (C-Brand). A consumption of 1 to 3 servings/day was established. One serving (200 mL) of soybean beverage offered a contribution percentage over the ADI (acceptable daily intake) for infants and children. Teenagers and adults did not exceed the ADI (10 mg/day). The consumption of soy beverages contributes significantly to the daily intake of fluoride, which could exceed the ADI with a consequent health risk. It is recommended to control the fluoride levels in the raw material and in the final product to assure the safety of these products.

Fluoride levels in river water from the volcanic regions of Cauca (Colombia)

Fluoride concentrations of 0.5 mg/L in drinking water are considered useful for dental caries prevention. However, fluoride concentrations higher than 1.2 mg/L in water can pose a risk of dental fluorosis due to high exposure to fluoride. The objective is to determine the fluoride concentration in water from aqueducts of different Colombian municipalities of Cauca (Popayán, Coconuco, and Puracé) to assess the fluoride dietary intake from the consumption of this water. A total of 66 water samples have been taken from Popayán, Coconuco, and Puracé. Fluoride content was determined by fluoride ion-selective electrode (ISE) potentiometry. The fluoride concentrations recorded in Coconuco and Puracé water were ≤ 0.002 mg/L. The mean fluoride content recorded in the Popayán water was 0.42 mg/L, with its highest concentration in Cauca River water (0.83 mg/L). Considering the admissible intake values, the water from Popayán confers remarkable fluoride intakes, especially in children with high percentages of contribution to the admissible daily intake (46.7% to 7- to 12-month children and 41.5% to 1- to 3-year children). The fluoride content in the water of Coconuco and Puracé does not reach an optimal value (< 0.5 mg/L) for the protective effect against dental caries, while the water of the main Cauca River basin does reach the optimal value. Likewise, the intake of fluoride from the consumption of the analyzed water does not confer any health risk. However, the implementation of monitoring systems for fluoride levels is recommended in order to safeguard the consumer's health.

Dietary Intake of Essential Elements (Na, K, Mg, Ca, Mn, Zn, Fe, Cu, Mo, Co) from Tofu Consumption

Tofu is one of the most consumed soybean products. Currently, tofu is consumed in vegan and vegetarian diets to avoid meat. However, it is necessary to determine the content of essential elements to assess the dietary intake. Essential elements (Na, K, Mg, Ca, Mn, Zn, Fe, Cu, Mo, Co) were determined in 130 samples of tofu by ICP-OES (inductively coupled plasma optical emission spectroscopy). The highest element content was found in flavoured tofu; the most notable were Na (2519 mg/kg wet weight) and Fe (19.5 mg/kg ww). Consumption of 200 g/day of flavoured tofu by adults would mean a high contribution of Cu (46.9% women, 38.1% men), Fe (55.7% women, 65.0% men) and Na (25.2% adults) to its AI (adequate intakes) sets by the EFSA (European Food Safety Authority). Natural tofu would mean a remarkably Mn contribution (50% adults) to the AI. Tofu could be an important source of essential elements such as Mg, Mn, Na, Cu and Fe.

Human exposure to fluoride from tea (Camellia sinensis) in a volcanic region-Canary Islands, Spain

Fluoride is highly present in the environment, especially in water and its derivatives. Excessive fluoride contribution to diet poses a health risk. Tea leaves accumulate fluoride and the consumption of tea (Camellia sinensis) could pose a risk to human by the excessive fluoride intake. Ninety tea samples were analyzed by potentiometry using a selective fluoride ion electrode. Mixed tea samples (2.82 ± 1.11 mg/L) and black tea samples (2.28 ± 0.79 mg/L) recorded the highest fluoride levels. The contribution of drinking water is important for increasing fluoride levels in teas. The daily consumption of two cups (250 mL per cup) of mixed and black teas prepared with La Laguna tap water does pose a health risk for children (4-8 years old) because of the high contribution percentages (74.4% and 63.6%, respectively) of the Tolerable Upper Intake Level set in 2.5 mg/day by the EFSA (European Food Safety Authority). A minor consumption in children (4-8 years old) and adults during pregnancy is advisable.

Macroelement, trace element, and toxic metal levels in leaves and infusions of yerba mate (Ilex paraguariensis)

Mate is an infusion made from the dried leaves of yerba mate (Ilex paraguariensis). Yerba mate may be an important source of essential elements but could contain toxicologically relevant metals. Macroelements (Ca, Mg, Na, K), trace elements (B, Ba, Sr, V, Li, Ni, Fe, Zn, Cu, Cr, Co, Mn, Mo), and toxic metals (Al, Cd, Pb) content have been determined in 32 samples of yerba mate by ICP-OES (inductively coupled plasma-optical emission spectrometry) with the aim of determining the element content of yerba mate leaves and the influence of temperature in the extraction of these elements from the plant to the infusion, and estimating the dietary intake for each element studied. The highest element contents have been found in infusions prepared with hot distilled water (70-75 °C); the most noteworthy are K (303 mg/L), Mn (4.85 mg/L), and Al (4.52 mg/L). The consumption recommended by the producers (500 mL infusion/day) contributes significantly to the daily intake of essential elements such as Mn, Mg, and Cu. This consumption does not pose a health risk, although it is necessary to assess the risk/benefit of Ni intake from mate consumption for people with impaired renal function (500 mL/day accounts for 52.2% of the TDI).

Effect of Fluoride Concentration in Drinking Water on Dental Fluorosis in Southwest Saudi Arabia

This study was intended to evaluate the fluoride concentration in drinking water and its effect on dental fluorosis in Southwest Saudi Arabia. Water samples were gathered rom wells, filtration plants and commercial brands (bottled water) in distinct urban and rural areas of Asir region of the Kingdom of Saudi Arabia (KSA). Overall, 63 water samples were collected from 12 locations and 9 brands of bottled water. ExStik^® FL700Fluoridemeter was used in the analysis of water samples for fluoride levels. The total number of screened patients for dental fluorosis, aged between 9 and 50 years, was 1150; among them, 609 were males and 541 were females. Dean's index criteria were used to examine the patients for dental fluorosis. The results revealed that fluoride levels varied between 0.03 and 3.8 ppm. People who drank well water displayed increased fluoride levels (>0.81 ppm). The prevalence of dental fluorosis was established to be 20.43% among the total number of examined patients. The findings of this study show very mild to moderate dental fluorosis prevail among the patients who consume well water in the Asir region.