Identifying Unknown Fluorine-Containing Compounds in Environmental Samples Using 19F NMR and Spectral Database Matching.

The ubiquity of per- and polyfluorinated alkyl substances (PFAS) in the environment is a continuing concern. While typical analytical methods for the analysis of PFAS include both targeted and non-targeted mass spectrometry, there remains a significant portion of fluorinated compounds that are not accounted for by these routine methods. It has been previously demonstrated that 19F NMR can be used to identify these compounds, helping to close the mass balance on total fluorine in the environment. 19F NMR offers an unbiased method of analysis that requires no anticipation of fluorine-carbon bonds or functional groups. However, there is resistance to further uptake of NMR spectroscopy as an analytical tool, owing to perceived difficulties in sensitivity and spectral overlap. In this study, we measure the 19F NMR spectrum of hundreds of fluorinated compounds and use this constructed database to determine the concentration of PFAS in an extracted sample of a known aqueous firefighting foam-contaminated site. The 19F NMR database has been included for use by other researchers, and we discuss the intricacies of 19F NMR as applied to environmental samples.

Analysis of fluorinated compounds by micellar electrokinetic chromatography - mass spectrometry.

Micellar electrokinetic chromatography (MEKC) is a good separation technique with high efficiency, high selectivity and simple preparation process. Hyphenation of MEKC with mass spectrometry (MS) could extend its application in complex sample analysis. However, direct coupling MEKC using commonly used surfactants like sodium dodecyl sulfate (SDS) with ESI-MS will lead to strong signal suppression. In this work, a MEKC-MS method using volatile ammonium perfluorooctanoate as surfactant was developed. The MS compatibility of ammonium perfluorooctanoate was investigated. The result revealed that there is no signal suppression even the concentration of ammonium perfluorooctanoate was up to 300 mM. Meanwhile, we found that ammonium perfluorooctanoate used as surfactant in MEKC provided powerful F-F interaction and hydrophobic interaction, which was beneficial for separation of fluorinated compounds. Using the ammonium perfluorooctanoate based MEKC method, several groups of fluorinated compounds, which cannot be separated using non-fluorinated surfactants like lauric acid and SDS based MEKC method, were baseline separated. Finally, the MEKC-ESI-MS method was successfully applied for analysis of two herbicides including fluometuron and fenuron in lake water samples with high separation efficiency, high sensitivity, good linearity and reproducibility.

First-trimester maternal concentrations of polyfluoroalkyl substances and fetal growth throughout pregnancy.

BACKGROUND: Several studies have investigated the possible association between prenatal exposure to perfluoroalkyl substances (PFASs) and birth anthropometry. However, none has assessed fetal size longitudinally. We studied the possible association between PFASs and fetal biometry. METHODS: In 1230 mother-child pairs of three cohorts from the Spanish INMA-Project, we analyzed perfluorohexanesulfonic acid (PFHxS), perfluorooctanesulfonic acid (PFOS), perfluorooctanoic acid (PFOA), and perfluorononanoic acid (PFNA) in first-trimester maternal plasma (collection: 2003-2008). We measured abdominal circumference (AC), femur length (FL), biparietal diameter (BPD), and estimated fetal weight (EFW) by ultrasounds at 12, 20, and 34 gestational weeks. We conducted multivariable linear regression analyses between log2-transformed (PFASs) and SD-scores of fetal parameters in each cohort and subsequent meta-analysis. We also assessed effect modification by sex and maternal smoking. RESULTS: PFHxS, PFOA, PFOS, and PFNA medians were: 0.58, 2.35, 6.05, and 0.65 ng/mL, respectively. There were no associations for the whole population in any trimester of pregnancy. However, we found an indication that maternal smoking modified the effect in different directions depending on the PFAS. Among smokers (31%), we found negative associations between both PFOA and PFNA and FL or EFW at week 20 (% change ranging between -6.8% and -5.7% per twofold PFAS increase) and positive associations between PFHxS or PFOS and BPD at week 34 (6.8% and 6.3%, respectively). CONCLUSIONS: Results did not suggest an overall association between prenatal PFASs and fetal growth. The results among smokers should be taken with caution and further studies are warranted to elucidate the possible role of smoking in this association.

Effect of fluoride slow-release glass devices on salivary and gingival crevicular fluid levels of fluoride: A pilot study.

Objectives: To estimate the effect of fluoride slow-release glass devices on the levels of fluoride in a pooled sample of human gingival crevicular fluid and in human saliva. Materials and Methods: Ten healthy adult volunteers wore fluoride slow-release glass devices for 3 months in a longitudinal experimental clinical pilot study. Whole unstimulated human saliva and gingival crevicular fluid were collected using paper points at baseline, after 2 weeks and at 3 months and analysed for their fluoride levels using ion chromatography and fluoride electrode. Results: No adverse effects were reported, and the Löe Plaque and Gingival Index remained low (0.22). The saliva determination of fluoride using the fluoride electrode showed an increase after 3 months from 0.02 ± 0.04 ppm to 0.06 ± 0.12 ppm, whereas the ion chromatography showed an increase from 0.15 ± 0.10 ppm to 0.44 ± 0.36 ppm. The fluoride levels in a pooled sample of gingival crevicular fluid from four intraoral sites were determined using the ion chromatography, and the results showed that after 3 months, the fluoride levels were still low (0.71 ± 0.34 ppb) similar to those at baseline (0.74 ± 0.31 ppb). Conclusions: The fluoride concentration in a pooled sample of gingival crevicular fluid was reported to be low with a range from 0.46 to 0.75 ppb and was not changed by placement of fluoride slow-release glass devices. The fluoride concentration in unstimulated human saliva showed an increase after 3 months when the fluoride slow-release glass devices were attached when determined with both the fluoride electrode (from .02 ± 0.04 ppm to 0.06 ± 0.12 ppm) and ion chromatography (from 0.15 ± 0.10 ppm to 0.44 ± 0.36 ppm).

Concentrations of organochlorine pesticides, polybrominated diphenyl ethers and perfluorinated compounds in the atmosphere of North Greenland.

Atmospheric concentrations of organochlorine pesticides (OCPs), polybrominated diphenyl ethers (PBDEs) and neutral per- and polyfluoroalkyl substances (PFAS) have been measured at Villum Research Station, Station Nord (North Greenland) in the period 2008-2013. Atmospheric concentrations of OCPs at the same site have been previously reported for the years 2008-2010. The detection frequency and the average concentrations of OCPs have not significantly changed since the previous study. PBDE congeners (∑13PBDEs) were measured for the first time in North Greenland at concentrations similar to those observed for other remote sites, confirming that these compounds are ubiquitous in the Northern Hemisphere. The ∑13PBDEs concentration ranged from not detected (n.d.) to 6.26 pg m(-3). The BDE congeners found in more than 30% of the samples were BDE-17, BDE-28, BDE-47, BDE-71, BDE-99 and BDE-100. Also for neutral PFAS we present for the first time a multiyear series of measurements for North Greenland. The average sum of the seven measured neutral PFAS (∑7PFAS) ranged from 1.82 to 32.1 pg m(-3). The most abundant compound was 8:2 FTOH (44% of ∑7PFAS), followed by 6:2 FTOH and 10:2 FTOH. Perfluoroalkyl sulfonamides (FOSA) and perfluoroalkyl sulfonamidoethanols (FOSE) were also detected but at much lower concentrations than FTOHs. Temporal trends were investigated for all measured compounds but no significant trend in concentration was observed. Monthly average concentrations for the six years were calculated for each compound and the seasonal variation was investigated. Some OCPs and FTOHs showed seasonal variations, and in most cases a maximum was found during summer.

[Environmental pollution with fluoride compounds and their influence on children health].

Data of hygienic studies of air and soil during last 20 years have confirmed their correlating relationship with the general morbidity and a group of musculoskeletal diseases in children living in cities with the technogenic pollution of the environment. Their bones were established to grow unevenly and disproportionally, in 76% of children there have been violations in the development and growth of bones. The results of X-ray examination of hand bones in children and adolescents in the Irkutsk and Shelekhov cities are presented. Significant differences in morbidity patterns among children and adolescents including an increased incidence of musculoskeletal diseases by 5.6 in children and by 12 in adolescents have been revealed.

[Thyroid gland pathology in children population exposed to the combination of iodine deficiency and fluoride pollution of environment].

The article presents results of study of the impact of iodine deficiency and technogenic fluoride on the state of the thyroid gland in children. On the example of two districts of the city of Bratsk there were executed dynamic investigations (2002 and 2012), including the estimation of the pollution of ambient air and soil by fluorine compounds, levels of iodine intake by the body, the clinical examination of children aged from 5 to 7 years d and interviewing of their parents. In the course of the medical examination there were executed: physical examination by the pediatrician, endocrinologist, ultrasound examination of the thyroid gland, the determination both of serum hormone content by radioimmunoassay and urinary excretion offluorine and iodine. Concentrations of hydrogen fluoride and a solidfluorides in ambient air led to the accumulation offluoride ion in the soil. The iodine entering with drinking water and food, was established to provide only 37.5-50% of the daily requirement of iodine. Increased fluoride ion content in urine and milk teeth in children is associated with the concentrations of the fluorine-containing pollutants in the ambient air and soil. The fluoride pollution against the background of the natural iodine deficiency was established to increase the frequency of functional and morphological disorders of the thyroid gland in children.

[Analysis on 24 Samples of Fluoritum by XRD Pattern].

Objective: To provide the reference for effective identification of Fluoritum,by using X-ray diffraction technique to analyze Fluoritum samples which had different morphological features. Methods: According to the China Pharmacopeia( 2010 edition),the24 samples of commercial Fluoritum were identified and their contents of Ca F2 were determined. XRD technique was applied to analyze phase compositions and content from Fluoritum samples, to ensure quality, and to summarize the correlation between traits and quality. Results: Sample 1 ~ 7 and 13 were Fluoritum, samples 8 ~ 12 were inferior products which were doped, and sample 14 ~ 24 were counterfeit products. Fluorite was the main phase of Fluoritum, and often accompanying a small amount of quartz. Phase compositions of counterfeit Fluoritum whose impurity content were high were relatively complicated, and the contents of Ca F2 were far below the standards value of the China Pharmacopeia( 2010 edition). Fluoritum were easy to be shattered into tiny sand which were green or purple, hyaline and lustered, with color becoming shallow. Conclusion: By picking to remove impurity, inferior products can be used for medicine. Because impurity content are high and the impurities are difficult to be separated, counterfeit products can not be used for medicine. Characteristics of powder can be used for supplement the identification for Fluoritum. And using XRD technique can accurately identify Fluoritum samples which have different morphological features.

Application of (19) F time-domain NMR to measure content in fluorine-containing drug products.

It is necessary to show that the active content in the dosage form of drugs is within a certain narrow range of the label claim. In case of fluorinated drugs, the active content can be measured by high field solid state NMR because the excipients lack fluorine. To make NMR reachable to any laboratory, simple to use, and at a low cost, measurement of (19) F nucleus using a 23 MHz (for (1) H) low field benchtop time-domain (TD) NMR was investigated. Three fluorinated drug products, cinacalcet, lansoprazole, and ciprofloxacin, were chosen for this study. The doses for these drug products range from 15 to 500 mg. The average drug content measured using (19) F TD-NMR compares well with the reported label claims for the three drugs tested. (19) F TD-NMR is a simple and non-destructive technique to measure drug content in tablets. In addition, the accessibility and simplicity of the technique makes it an excellent process analytical technology tool for development and manufacturing in the pharmaceutical industry. Copyright © 2015 John Wiley & Sons, Ltd.

Fluoruro en aguas minerales naturales envasadas en España y prevención de la caries dental / Fluoride content of bottled natural mineral waters in Spain and prevention of dental caries

OBJETIVO: El propósito del estudio es conocer la concentración en flúor de las aguas minerales naturales comercializadas en España para poder prevenir la caries dental sin el riesgo de causar fluorosis dental. DISEÑO: Estudio descriptivo y transversal a lo largo de 2012. Emplazamiento: Aguas minerales naturales comercializadas en España. PARTICIPANTES: Tres muestras con fechas distintas de embotellado de 109 marcas de aguas minerales naturales (97 marcas españolas y 12 aguas importadas). Medición principal: Determinación analítica por cromatografía iónica del contenido en fluoruro en el agua. RESULTADOS: La concentración mediana de fluoruro de las aguas minerales naturales españolas es de 0,22 (rango 0,00-4,16; rango intercuartil: 0,37). La gran mayoría (61 marcas, 62%) contenían menos de 0,30 mg/L. Hay 19 marcas que contienen más de 0,6 mg/L. Hay 19 marcas españolas que contienen más de 0,6 mg/L. En las 12 aguas minerales importadas, la mediana es de 0,35 (rango 0,10-1,21; rango intercuartil: 0,23). Sólo en 28 de las 109 marcas examinadas (25,6%) se especificaba el contenido de fluoruro en la etiqueta. Se observa una buena correlación entre las concentraciones indicadas y los valores analizados. CONCLUSIONES: Las concentraciones de fluoruro en las aguas minerales naturales comercializadas en España muestran una gran variabilidad. Dado el creciente consumo de las aguas minerales naturales en España, este tipo de información es de suma importancia para poder hacer una correcta utilización de flúor en la prevención primaria de la caries dental

AIM: The aim of the study was to determine the concentration of fluoride in natural mineral waters marketed in Spain in order to prevent tooth decay without the risk of causing dental fluorosis DESIGN: Descriptive and cross-sectional study during 2012. LOCATION: Natural mineral waters marketed in Spain. PARTICIPANTS: Three bottles with different bottling dates of 109 natural mineral waters (97 Spanish and 12 imported brands). Main measures: Determination of fluoride by ion chromatography RESULTS: Median fluoride concentrations of the natural mineral waters bottled in Spain was 0.22 (range 0.00-4.16; interquartile range:0.37). Most samples (61 brands, 62%) contained less than 0.3 mg/L. There are 19 Spanish brands with more than 0.6 mg/L. The median level in imported brands was 0.35 (range 0.10-1.21; interquartile range: 0.23). Only 28 of the 109 brands examined (25.6%) specified the fluoride content on the label. Good correlation was observed between the concentrations indicated and those determined. CONCLUSIONS: Fluoride concentrations in natural mineral waters showed high variation. Given the growing consumption of natural mineral waters in Spain, this type of information is important to make proper use of fluoride in the primary prevention of dental caries

Determination of perfluorinated carboxylic acids in fish fillet by micro-solid phase extraction, followed by liquid chromatography-triple quadrupole mass spectrometry.

In the current study, a simple, fast and efficient combination of protein precipitation and micro-solid phase extraction (µ-SPE) followed by liquid chromatography-triple quadrupole tandem mass spectrometry (LC-MS/MS) was developed for the determination of perfluorinated carboxylic acids (PFCAs) in fish fillet. Ten PFCAs with different hydrocarbon chain lengths (C5-C14) were analysed simultaneously using this method. Protein precipitation by acetonitrile and µ-SPE by surfactant-incorporated ordered mesoporous silica were applied to the extraction and concentration of the PFCAs as well as for removal of interferences. Determination of the PFCAs was carried out by LC-MS/MS in negative electrospray ionization mode. MS/MS parameters were optimized for multiple reaction monitoring of the analytes. (13)C mass labelled PFOA as a stable-isotopic internal standard, was used for calibration. The detection limits of the method ranged from 0.97 ng/g to 2.7 ng/g, with a relative standard deviation of between 5.4 and 13.5. The recoveries were evaluated for each analyte and were ranged from 77% to 120%. The t-test at 95% confidence level showed that for all the analytes, the relative recoveries did not depend on their concentrations in the explored concentration range. The effect of the matrix on MS signals (suppression or enhancement) was also evaluated. Contamination at low levels was detected for some analytes in the fish samples. The protective role of the polypropylene membrane used in µ-SPE in the elimination of matrix effects was evaluated by parallel experiments in classical dispersive solid phase extraction. The results evidently showed that the polypropylene membrane was significantly effective in reducing matrix effects.

Historical trends of inorganic and organic fluorine in sediments of Lake Michigan.

Total fluorine (TF), extractable organic fluorine (EOF) and poly- and per-fluorinated compounds (PFCs) were measured in eight dated cores of sediment taken along with 27 surface sediments from Lake Michigan in 2010. Based on rates of sedimentation, total concentrations of PFCs (∑PFCs) reached a maximum in the later 1990s and early 2000s. This result is consistent with rapid changes in production and subsequent sedimentation. Perfluorooctanesulfonate (PFOS) and perfluorooctanoate (PFOA) are still the predominant PFCs in the cores, but in surface sediments, concentrations of perfluorobutane sulfonate (PFBS) and perfluorobutanoic acid (PFBA) are now occurring at concentrations comparable to those of PFOS and PFOA. This observation is consistent with shifts in patterns of production and use in the US and Canada. Concentrations of TF in sediments were greater than those of EOF. This result is consistent with a larger proportion of un-extractable fluorinated material in both surface sediments and in cores.

Determination of perfluorinated alkyl acids in corn, popcorn and popcorn bags before and after cooking by focused ultrasound solid-liquid extraction, liquid chromatography and quadrupole-time of flight mass spectrometry.

An analytical method is proposed to determine ten perfluorinated alkyl acids (PFAAs) [nine perfluorocarboxylic acids (PFCAs) and perfluorooctane sulfonate (PFOS)] in corn, popcorn and microwave popcorn packaging by focused ultrasound solid-liquid extraction (FUSLE) and ultra high performance liquid chromatography (UHPLC) coupled to quadrupole-time of flight mass spectrometry (QTOF-MS/MS). Selected PFAAs were extracted efficiently in only one 10-s cycle by FUSLE, a simple, safe and inexpensive technique. The developed method was validated for microwave popcorn bags matrix as well as corn and popcorn matrices in terms of linearity, matrix effect error, detection and quantification limits, repeatability and recovery values. The method showed good accuracy with recovery values around 100% except for the lowest chain length PFAAs, satisfactory reproducibility with RSDs under 16%, and sensitivity with limits of detection in the order of hundreds picograms per gram of sample (between 0.2 and 0.7ng/g). This method was also applied to the analysis of six microwave popcorn bags and the popcorn inside before and after cooking. PFCAs contents between 3.50ng/g and 750ng/g were found in bags, being PFHxA (perfluorohexanoic acid) the most abundant of them. However, no PFAAs were detected either corn or popcorn, therefore no migration was assumed.

A method for the analysis of perfluorinated compounds in environmental and drinking waters and the determination of their lowest concentration minimal reporting levels.

A trace analytical method was developed for the determination of seventeen specific perfluorinated chemicals (PFCs) in environmental and drinking waters. The objectives were to optimize an isotope-dilution method to increase the precision and accuracy of the analysis of the PFCs and to eliminate the need for matrix-matched standards. A 250 mL sample of environmental or drinking water was buffered to a pH of 4, spiked with labeled surrogate standards, extracted through solid phase extraction cartridges, and eluted with ammonium hydroxide in methyl tert-butyl ether: methanol solution. The sample eluents were concentrated to volume and analyzed by liquid chromatography/tandem mass spectrometry (LC-MS/MS). The lowest concentration minimal reporting levels (LCMRLs) for the seventeen PFCs were calculated and ranged from 0.034 to 0.600 ng/L for surface water and from 0.033 to 0.640 ng/L for drinking water. The relative standard deviations (RSDs) for all compounds were <20% for all concentrations above the LCMRL. The method proved effective and cost efficient and addressed the problems with the recovery of perfluorobutanoic acid (PFBA) and other short chain PFCs. Various surface water and drinking water samples were used during method development to optimize this method. The method was used to evaluate samples from the Mississippi River at New Orleans and drinking water samples from a private residence in that same city. The method was also used to determine PFC contamination in well water samples from a fire training area where perfluorinated foams were used in training to extinguish fires.

Identification of novel fluorinated surfactants in aqueous film forming foams and commercial surfactant concentrates.

Recent studies comparing the results of total organofluorine-combustion ion chromatography (TOF-CIC) to targeted analysis of perfluoroalkyl and polyfluoroalkyl substances (PFASs) by liquid chromatography tandem mass spectrometry (LC-MS/MS) have shown that a significant yet variable portion of the total organofluorine in environmental and biological samples is in the form of unknown PFASs. A portion of this unknown organofluorine likely originates in proprietary fluorinated surfactants not included in LC-MS/MS analyses and not fully characterized by the environmental science community, which may enter the environment through use in aqueous film forming foams (AFFFs) for firefighting. Contamination of water, biota, and soils with various PFASs due to AFFF deployment has been documented. Ten fluorinated AFFF concentrates, 9 of which were obtained from fire sites in Ontario, Canada, and two commercial fluorinated surfactant concentrates were characterized in order to identify novel fluorinated surfactants. Mixed-mode ion exchange solid phase extraction (SPE) fractionated fluorinated surfactants based on ionic character. High resolution mass spectrometry assigned molecular formulas to fluorinated surfactant ions, while collision induced dissociation (CID) spectra assisted structural elucidation. LC-MS/MS detected isomers and low abundance fluorinated chain lengths. In total, 12 novel and 10 infrequently reported PFAS classes were identified in fluorinated chain lengths from C3 to C15 for a total of 103 compounds. Further research should examine the environmental fate and toxicology of these PFASs, especially their potential as perfluoroalkyl acid (PFAA) precursors.

Fluorine detected 2D NMR experiments for the practical determination of size and sign of homonuclear F-F and heteronuclear C-F multiple bond J-coupling constants in multiple fluorinated compounds.

The use of fluorine in molecules obtained from chemical synthesis has become increasingly important within the pharmaceutical and agricultural industry. NMR characterization of these compounds is of great value with respect to their structure elucidation, their screening in metabolomics investigations and binding studies. The favorable NMR properties of the fluorine nucleus make NMR with fluorine detection of great value in this respect. A suite of NMR 2D F-F- and F-C-correlation experiments with fluorine detection was applied to the assignment of resonances, (n)J(CF)- and (n)J(FF)-couplings as well as the determination of their size and sign. The utilization of this experiment suite was exemplarily demonstrated for a highly fluorinated vinyl alkyl ether. Especially F-C HSQC and J-scaled F-C HMBC experiments allowed determining the size of the J-couplings of this compound. The relative sign of its homo- and heteronuclear couplings was achieved by different combinations of 2D NMR experiments, including non-selective and F2-selective F-C XLOC, F2-selective F-C HMQC, and F-F COSY. The F2-one/two-site selective F-C XLOC versions were found highly useful, as they led to simplifications of the common E.COSY patterns and resulted in a higher confidence level of the assignment by using selective excitation. The combination of F2-one/two-site selective F-C XLOC experiments with a F2-one-site selective F-C HMQC experiment provided the signs of all (n)J(CF)- and (n)J(FF)-couplings in the vinyl moiety of the test compound. Other combinations of experiments were found useful as well for special purposes when focusing for example on homonuclear couplings a combination of F-F COSY-10 with a F2-one-site selective F-C HMQC could be used. The E.COSY patterns in the spectra demonstrated were analyzed by use of the spin-selective displacement vectors, and in case of the XLOC also by use of the DQ- and ZQ-displacement vectors. The variety of experiments presented shall contribute to facilitate the interpretation of F-C correlations as well as to open alternative pathways for the determination of size and signs of homo- and heteronuclear couplings of multiply fluorinated small molecules.

Aplicação de diferentes agentes fluoretados para prevenção de erosão e abrasão do esmalte in vitro / Application of different fluoridated agents for the prevention of enamel erosion and abrasion in vitro

O objetivo deste estudo foi investigar o potencial inibidor de desgaste dentário ocasionado por erosão e abrasão de um novo produto, o verniz ClinPro XT Varnish, em comparação com vernizes fluoretados convencionais à base de TiF4 e NaF. Sessenta amostras de esmalte bovino (n=15/grupo) com microdureza superficial entre 300-380KHN foram selecionadas e aleatoriamente tratadas com: verniz de NaF (Duraphat®, 2,26% F-), verniz de TiF4 (2,45% F-), ClinPro XT varnish (fluoraluminiosilicato e glicerofosfato de cálcio) e controle (sem tratamento). Após receberem os respectivos tratamentos, as amostras foram submetidas a 3 dias de desafios erosivos de 4x5 min/dia (Sprite® Zero) e a abrasão 2x15s/dia, utilizando uma máquina de escovação. Entre os ciclos de erosão e abrasão, as amostras permaneceram em saliva artificial. A perda de esmalte foi medida com perfilômetro óptico. Os dados foram submetidos ao teste Kruskal-Wallis seguido pelo Dunn (p<0,05) .Ambos vernizes de NaF (-5,84m [-12,06; 1,64]b) (mediana ± 95%IC) e TiF4 (-3,60m [-8,72; -0,45]b) foram eficazes em reduzir o desgaste do esmalte quando comparados ao grupo controle (-16,60m [-19,92; -10,04]a). O ClinPro XT varnish permaneceu na superfície do esmalte (106,21m [30,67; 126,22]c), impedindo completamente o desgaste. Assim foi possível concluir que o ClinPro XT teve um efeito superior aos outros vernizes, impedindo completamente a erosão e abrasão do esmalte por 3 dias in vitro.

The purpose of this study was to investigate the erosion and abrasion inhibiting effect of a newly released product, Vanish XT varnish, and compare it to conventional TiF4 and NaF varnishes. Sixty bovine enamel blocks (300-380 KHN) were selected and randomly allocated into 4 treatment groups (n=15/group): NaF varnish (Duraphat®, 2.26% F-), TiF4 varnish (2.45% F-), Vanish XT varnish (fluoroaluminosilicate and calcium glycerophosphate), and control (no treatment). The samples received their respective treatments one single time at the beginning of the experiment. During a total of 3 days, erosive challenges were done 4x5min/day (Sprite Zero®) and abrasion 2x15s/day using a brushing machine. In between the erosive and abrasive challenges and overnight the samples remained immersed in artificial saliva. Enamel loss was measured using a non-contact profilometer. The data were subjected to Kruskal-Wallis and Dunn tests (p<0.05). Both NaF (-5.84m [-12.06; 1.64]b) (median ± 95%CI) and TiF4 (-3.60m [-8.72; -0.45]b) varnishes were able to reduce enamel wear when compared to the control group (-16.60m [-19.92; -10.04]a). Vanish XT varnish remained on the enamel surface (106.21m [30.67; 126.22]c), completely preventing enamel wear. Therefore, we concluded that Vanish XT presented a superior effect when compared to conventional varnishes, completely preventing enamel erosion and abrasion for 3 days in vitro.

In-situ molecular-level elucidation of organofluorine binding sites in a whole peat soil.

The chemical nature of xenobiotic binding sites in soils is of vital importance to environmental biogeochemistry. Interactions between xenobiotics and the naturally occurring organic constituents of soils are strongly correlated to environmental persistence, bioaccessibility, and ecotoxicity. Nevertheless, because of the complex structural and chemical heterogeneity of soils, studies of these interactions are most commonly performed indirectly, using correlative methods, fractionation, or chemical modification. Here we identify the organic components of an unmodified peat soil where some organofluorine xenobiotic compounds interact using direct molecular-level methods. Using (19)F→(1)H cross-polarization magic angle spinning (CP-MAS) nuclear magnetic resonance (NMR) spectroscopy, the (19)F nuclei of organofluorine compounds are used to induce observable transverse magnetization in the (1)H nuclei of organic components of the soil with which they interact after sorption. The observed (19)F→(1)H CP-MAS spectra and dynamics are compared to those produced using model soil organic compounds, lignin and albumin. It is found that lignin-like components can account for the interactions observed in this soil for heptafluoronaphthol (HFNap) while protein structures can account for the interactions observed for perfluorooctanoic acid (PFOA). This study employs novel comprehensive multi-phase (CMP) NMR technology that permits the application of solution-, gel-, and solid-state NMR experiments on intact soil samples in their swollen state.

Modeled comparisons of health risks posed by fluorinated solvents in a workplace spill scenario.

The purpose of this study was to illustrate how available physical-chemical exposure models can be used to compare potential risks and define risk management measures for non-routine exposure events, such as spills, leaks, or process upset conditions. A two-zone physical-chemical model was used to quantify and compare the potential exposure risks from five fluorinated solvents used in the manufacturing of electronic materials during an anticipated spill scenario. A 1-l spill scenario in a room measuring 2.74 m (9 ft) high by 3.66 m (12 ft) wide by 9.14 m (30 ft) long was constructed for modeling exposures using 'The Two-zone Model with An Exponentially Decreasing Contaminant' in available freeware 'IH MOD' (a PC based program available from the American Industrial Hygiene Association). This treatment was followed by using the results from an experimental chamber study in which the evaporation rates and vapor concentrations of the five fluorinated solvents were measured under realistic conditions and then compared to exposure model outputs. The breathing zone concentration/time profiles predicted for the five solvents were compared to their exposure limits to estimate the relative risk. This information was used to help define operationally sufficient risk management options for the safe handling of spills in laboratories, warehouses, or manufacturing facilities. The model indicated that each solvent presented very different risk profiles for the same 1-l liquid spill scenario. Potential exposure concentrations relative to short-term exposure limit (15 min) and Ceiling (C) exposure limit available for some of the solvents are predicted to be exceeded within a few minutes in the area near the spill and in the far field. In addition, the model showed that near-field concentrations for one solvent exceeded the published LC-50 (the concentration predicted to cause 50% mortality in the test animals), which indicates a very high degree of risk for this material in similar scenarios. Given the speed of evaporation during these spills for the materials tested in this study, donning personal protective equipment in the area may not be a viable option and short-term evacuation of the area immediately surrounding the spill would appear to be a practical risk management response.

Temporal and spatial trends of perfluorinated compounds in juvenile loggerhead sea turtles (Caretta caretta) along the East Coast of the United States.

Perfluorinated compounds (PFCs) are globally distributed persistent environmental contaminants. This study provides temporal trends as well as large-scale spatial trends of PFC concentrations in threatened juvenile loggerhead sea turtles near or from Florida Bay (FL Bay), Cape Canaveral (FL), Charleston (SC), Core Sound (NC), and Chesapeake Bay (MD). PFCs were extracted from 163 plasma and serum samples using solid-phase extraction and quantified with LC-MS/MS. Concentrations of six compounds significantly varied by site, with MD or FL Bay turtles having the highest concentrations. Perfluorooctane sulfonate (PFOS) was the predominant PFC at all sites (range: 0.31 ng/g to 39.0 ng/g). FL Bay turtles, compared to other sites, accumulated a unique PFC pattern with a higher proportion of perfluorocarboxylates compared to PFOS. Furthermore, this study was the first to statistically correlate wildlife PFC concentrations with human population, used as a proxy for urbanization and sources of PFCs to the environment. Positive relationships were found in which human population accounted for 75 and 81% of the variance in turtle PFOS and perfluoroundecanoate (PFUnA) concentrations (p = 0.06 and 0.04), respectively. PFOS and perfluorononanoate (PFNA) significantly decreased from 2000-2008 in SC turtles annually by 20 and 11%, respectively (p