A multi-platform approach for the comprehensive analysis of per- and polyfluoroalkyl substances (PFAS) and fluorine mass balance in commercial ski wax products.

The unique properties of per- and polyfluoroalkyl substances (PFAS) have led to their extensive use in consumer products, including ski wax. Based on the risks associated with PFAS, and to align with PFAS regulations, the international ski federation (FIS) implemented a ban on products containing "C8 fluorocarbons/perfluorooctanoate (PFOA)" at all FIS events from the 2021/2022 season, leading manufactures to shift their formulations towards short-chain PFAS chemistries. To date, most studies characterising PFAS in ski waxes have measured a suite of individual substances using targeted analytical approaches. However, the fraction of total fluorine (TF) in the wax accounted for by these substances remains unclear. In this study, we sought to address this question by applying a multi-platform, fluorine mass balance approach to a total of 10 commercially available ski wax products. Analysis of TF by combustion ion chromatography (CIC) revealed concentrations of 1040-51700 µg F g-1 for the different fluorinated waxes. In comparison, extractable organic fluorine (EOF) determined in methanol extracts by CIC (and later confirmed by inductively-coupled plasma-mass spectrometry and 19F- nuclear magnetic resonance spectroscopy) ranged from 92 to 3160 µg g-1, accounting for only 3-8.8 % of total fluorine (TF). Further characterisation of extracts by cyclic ion mobility-mass spectrometry (IMS) revealed 15 individual PFAS with perfluoroalkyl carboxylic acid concentrations up to 33 µg F g-1, and 3 products exceeding the regulatory limit for PFOA (0.025 µg g-1) by a factor of up to 100. The sum of all PFAS accounted for only 0.01-1.0 % of EOF, implying a high percentage of unidentified PFAS, thus, pyrolysis gas chromatography-mass spectrometry was used to provide evidence of the nature of the non-extractable fluorine present in the ski wax products.

Determination of total extractable organofluorine (EOF) in food contact materials and target and non-target analysis of per- and polyfluoroalkyl substances using LC-MS/MS and LC-HRMS simultaneously coupled to ICP-MS.

Food contact materials (FCMs) from three countries were analysed for all extractable organofluorines (EOFs) from the materials and subsequently by target and non-target analysis for per- and polyfluoroalkyl substances (PFAS). The EOF varied by two orders of magnitude for FCM from UK and Saudi Arabia ranging between 2.14 and 483 ng cm-2 (0.2-48 ng g-1) showing that one quarter of all samples were above the Danish regulation for PFAS in FCM. Target PFAS showed high variability in composition and accounted for less than 1% of the EOF. Non-target PFAS screening using HPLC-ICP-MS and coupled simultaneously to HRMS showed the occurrence of organofluorines which were identified by neither LC-MS/MS nor LC-HRMS. This illustrates that the current target PFAS approaches fail to identify EOFs from FCM, which would be a problem with the new EU proposal to ban all PFAS.

Speciation of arsenic in milk from cows fed seaweed.

BACKGROUND: Including seaweed in cattle feed has gained increased interest, but it is important to take into account that the concentration of toxic metals, especially arsenic, is high in seaweed. This study investigated the arsenic species in milk from seaweed-fed cows. RESULTS: Total arsenic in milk of control diets (9.3 ± 1.0 µg As kg-1, n = 4, dry mass) was significantly higher than seaweed-based diet (high-seaweed diet: 7.8 ± 0.4 µg As kg-1, P < 0.05, n = 4, dry mass; low-seaweed diet: 6.2 ± 1.0 µg As kg-1, P < 0.01, n = 4, dry mass). Arsenic speciation showed that the main species present were arsenobetaine (AB) and arsenate (As(V)) (37% and 24% of the total arsenic, respectively). Trace amounts of dimethylarsinic acid (DMA) and arsenocholine (AC) have also been detected in milk. Apart from arsenate being significantly lower (P < 0.001) in milk from seaweed-fed cows than in milk from the control group, other arsenic species showed no significant differences between groups. CONCLUSION: The lower total arsenic and arsenate in seaweed diet groups indicates a possible competition of uptake between arsenate and phosphate, and the presence of AC indicates that a reduction of AB occurred in the digestive tract. Feeding a seaweed blend (91% Ascophyllum nodosum and 9% Laminaria digitata) does not raise As-related safety concerns for milk. © 2024 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Analysis of per- and polyfluoroalkyl substances (PFAS) in raw materials intended for the production of paper-based food contact materials - evaluating LC-MS/MS versus total fluorine and extractable organic fluorine.

Per- and polyfluoroalkyl substances (PFAS) analysis has become crucial due to their presence in the environment, their persistence and potential health risks. These compounds are commonly used in food contact materials (FCM) as a coating to provide water and grease-repellent properties. One of the pathways for PFAS to enter the human body is either through direct consumption of contaminated food or indirectly through migration from FCM into food. The purpose of this study was to investigate where the initial contamination of paper FCM occurs. We analysed paper material consisting of fresh fibre and secondary materials, intended to produce food packaging for the presence of PFAS. The samples were extracted and analysed for 23 different PFAS substances using the targeted approach with LC tandem mass spectrometry (LC-MS/MS). This analytical technique detects specific, easily ionisable PFAS with high sensitivity. However, one drawback of this approach is that it allows the identification of less than 1% of the PFAS known today. For this reason, we used combustion ion chromatography (CIC) to determine the content of extractable organic fluorine compounds (EOF) and compare it to the total fluorine content. The targeted analysis using LC-MS/MS measured an average sum concentration of PFAS of 0.17 ng g-1 sample. Our research shows that the primary PFAS contamination happens during the recycling process since all of the samples in which the targeted PFAS were measured belonged to the secondary material. The most frequently detected analytes were PFOA and PFOS, detected in 90% and 62% of the samples, respectively, followed by PFBS (in 29% of the samples). CIC showed that measured PFAS via LC-MS/MS amount to an average of 2.7 × 10-4% of total fluorine content, whereas the EOF was under the LOD in all of the measured samples. This result highlights the complexity of the accurate determination of PFAS compounds, displaying what kind of information the chosen methods provide.

Fluorine mass balance analysis in wild boar organs from the Bohemian Forest National Park.

Wild boars have been reported as bioindicators for per- and polyfluoroalkyl substances (PFAS) in a variety of studies. However, data about PFAS levels in wild boars from sites with limited industrial and general human activity is scarce. In this study, wild boar (Sus scrofa) organs from the Bohemian Forest National Park (Czech Republic) were used as bioindicators for PFAS pollution. In this work, 29 livers and 24 kidneys from 30 wild boars (0.5-5 years) were investigated using a fluorine mass balance approach. For this, the samples were measured using high performance liquid chromatography with electrospray ionisation tandem mass spectrometry (HPLC-ESI-MS/MS), targeting 30 PFAS, including legacy and replacement PFAS, direct total oxidisable precursor assay (dTOPA) and combustion ion chromatography (CIC). Perfluorocarboxylic acids (PFCAs) from C7 to C14 and perfluorooctanesulfonic acid (PFOS) were detected in >50 % of samples. In the livers, PFCAs dominated the profile with median concentrations of 230 µg/kg for perfluorononanoic acid (PFNA) and 75 µg/kg perfluorooctanoic acid (PFOA). PFOA and PFNA concentrations in the livers were one order of magnitude higher than in livers from wild boars caught in rural NE Germany considered as background concentration. PFOS in liver contributed only 30 % to the Σc(PFASTarget) with a median concentration of 170 µg/kg. Kidneys and livers contain an average of 2460 µg F/kg and 6800 µg F/kg extractable organic fluorine (EOF) respectively. Σc(PFASTarget) add up to a maximum of 10 % of the extractable organic fluorine. After oxidisation of the samples, PFOA, PFNA and Σc(PFASdTOPA) increased in livers, but could not explain the EOF. The elevated concentration of PFOA and PFNA may indicate differences in biomagnification for different habitats or an unidentified PFAS source in proximity to the national park.

Lipophilic arsenic compounds in the cultured green alga Chlamydomonas reinhardtii.

In this study, arsenic (As) speciation was investigated in the freshwater alga Chlamydomonas reinhardtii treated with 20 µg/L arsenate using fractionation as well as ICP-MS/ESI-MS analyses and was compared with the known As metabolite profile of wild-grown Saccharina latissima. While the total As accumulation in C. reinhardtii was about 85% lower than in S. latissima, the relative percentage of arsenolipids was significantly higher in C. reinhardtii (57.0% vs. 5.01%). As-containing hydrocarbons and phospholipids dominated the hydrophobic As profile in S. latissima, but no As-containing hydrocarbons were detectable in C. reinhardtii. Instead for the first time, an arsenoriboside-containing phytol (AsSugPhytol) was found to dominate the hydrophobic arsenicals of C. reinhardtii. Interestingly, this compound and its relatives had so far been only found in green marine microalgae, open sea plankton (mixed assemblage), and sediments but not in brown or red macroalgae. This compound family might therefore relate to differences in the arsenic metabolism between the algae phyla.

Detection of inorganic arsenic in rice using a field-deployable method with Cola extraction.

Rice is a staple food and known to accumulate inorganic arsenic (iAs), which is a class 1 carcinogen to humans. Arsenic field-deployable method kits, designed for water testing, are able to screen iAs in rice, to assure food safety and quick decision-making without the need for laboratory analysis. For the arsenic extraction within the field method, nitric acid is used. To make the field method on-site safer, cost-effective and easier to handle, the method was adapted using a Cola in the extraction process. The adapted field-deployable method was tested by screening a total of 30 rice and rice products from the Austrian market. To verify the results obtained by the Cola extraction field-deployable method, the obtained iAs concentration was compared to HPLC-ICP-MS results. The Cola extraction field method obtained an LOD of 39 µg iAs kg-1 rice, and with an average reproducibility of 14% RSD, the method was capable of recording no false-negative but 7% false-positive values at the 2023 updated European Commission (EC) limits for rice. All, but one, screened rice samples were within the EU limits for iAs in rice and rice products.

Per and polyfluoroalkylated substances (PFAS) target and EOF analyses in ski wax, snowmelts, and soil from skiing areas.

Per and polyfluoroalkylated substances (PFAS) are common additives in ski waxes for their water repellent characteristic. Abrasion of ski wax leaves PFAS on the snow surface, however, little is known about the distribution and concentration of PFAS in snow and soil due to skiing. In this study we analysed different ski waxes, snowmelts and soil from family skiing areas from Alpine locations using targeted high performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS) to understand more about PFAS distribution in the environment. In general, we found a very diverse PFAS pattern in the analysed media. PFAS level was higher in skiing areas compared to the non-skiing ones that were used as control. ∑target PFAS ranged between <1.7 ng L-1 and 143 ng L-1 in snowmelt, <0.62 ng g-1 and 5.35 ng g-1 in soil and <1.89 and 874 ± 240 ng g-1 in ski wax samples. Snowmelt was dominated by short-chained PFAS, while soil and wax contained both short and long-chained PFAS. Extractable organic fluorine (EOF) was several orders of magnitude higher for waxes (0.5-2 mg g-1) than for soils (up to 0.3 µg g-1), while total fluorine (TF) content of the waxes was even higher, up to 31 210 ± 420 µg g-1. We also showed that the ∑ target PFAS accounts for up to 1.5% in EOF content, showing that targeted LC-MS/MS gives a limited measure of the pollution originated from ski waxes and non-targeted analysis and EOF is necessary for a better overview on PFAS distribution.

Fluorine mass balance analysis of PFAS in communal waters at a wastewater plant from Austria.

Wastewater treatment plants are a major source of per and polyfluoroalkyl substances (PFAS) in the environment; moreover, long chain PFAS are known to accumulate in sewage sludge. Although publications on PFAS in wastewater are available from around the globe, little information is available from Central Europe. In this study influent, effluent, and sludge from two wastewater treatment plants from Austria were analysed for target PFAS compounds with HPLC MS/MS and extractable organic fluorine (EOF) content with combustion ion chromatography (CIC). The sum of 31 target PFAS increased from 22 to 47 ng L-1 in influent to 140 - 213 ng L-1 in effluent and around 10 ng g-1 in sludge, while EOF were found to be consistent (2.3 - 3.5 µg F L-1) in influent/effluent and 280 ng F g-1 in sludge. Mass balance analysis showed an increase in the identified PFAS compounds in the effluent compared to the influent (from 0.9% - 1.3% to 3.6% - 6.1%), suggesting biotransformation of non-targeted PFAS precursor compounds. In conclusion, wastewater treatment plants transform some PFAS, and wastewater effluent is a source of PFAS contamination in surface water.

The impact of corrosion on the adsorption of gaseous Hg0 onto the surface of steels: Implications for decommissioning in the oil and gas industry.

The rate of decommissioning of global oil and gas production facilities will accelerate over coming decades, as mature developments reach the end of use, and consumers transition towards renewable energy. Decommissioning strategies should include thorough environmental risk assessments which consider contaminants which are known to be present in oil and gas systems. Mercury (Hg) is a global pollutant that occurs naturally in oil and gas reservoirs. However, knowledge of Hg contamination in transmission pipelines and process equipment is limited. We investigated the potential for accumulation of Hg0 within production facilities, particularly those transporting gases, by considering the deposition of Hg onto steel surfaces from the gas phase. Following incubation experiments in a Hg saturated atmosphere; fresh API 5L-X65 and L80-13Cr steels were found to adsorb 1.4 × 10-5 ± 0.04 × 10-5 and 1.1 × 10-5 ± 0.04 × 10-5 g m-2, respectively, while corroded samples of the same steels adsorbed 0.12 ± 0.01 and 0.83 ± 0.02 g m-2; an increase in adsorbed mercury by four orders of magnitude. The association between surface corrosion and Hg was demonstrated by laser ablation ICPMS. The levels of Hg measured on the corroded steel surfaces indicates a potential environmental risk; therefore, mercury speciation (including the presence of ß-HgS, not considered in this study), concentrations and cleaning methods should be considered when developing oil and gas decommissioning strategies.

Arsenic, cadmium, and lead in rice and rice products on the Austrian market.

Fifty-one rice samples, i.e. 25 rice varieties, 8 rice products, and 18 rice containing baby foods from the Austrian market were surveyed for arsenic, cadmium, and lead. Inorganic arsenic (iAs) is most toxic to human health, and its mean concentrations in rice were 120 µg kg-1, 191 µg kg-1 in rice products, and 77 µg kg-1 in baby foods. The average dimethylarsinic acid and methylarsonic acid concentrations were 56 µg kg-1 and 2 µg kg-1, respectively. The highest iAs concentration was found in rice flakes (237 ± 15 µg kg-1), close to the Maximum Level (ML) set by the EU regulation for husked rice (250 µg kg-1). The levels of cadmium (12 to 182 µg kg-1) and lead (6 to 30 µg kg-1) in the majority of rice samples were below the European ML. Upland grown rice from Austria showed both, low inorganic arsenic (<19 µg kg-1) and cadmium (<38 µg kg-1) concentrations.

EOF and target PFAS analysis in surface waters affected by sewage treatment effluents in Berlin, Germany.

Per- and polyfluoroalkyl substances (PFAS) are emerging organic pollutants and can occur in surface and groundwater. To identify the degree of pollution in surface water with PFAS, often targeted HPLC-ESI-MS/MS has been employed in which commonly 30-40 compounds are analyzed. However, other PFAS and organofluorines remain undetected. We sampled surface water of the river Spree and the Teltow Canal in Berlin, Germany, which are affected by the effluent discharge of wastewater treatment plants. Here, we employed high-resolution continuum source graphite furnace molecular absorption spectrometry (HR-CS-GFMAS) for measuring extractable organofluorines (EOF) and compared in a mass balance approach the total fluorine to the identified and quantified PFAS from the targeted analysis. The analysis highlights that the EOF are in the range expected for an urban river system (Winchell et al. in Sci Total Environ 774, 2021). However, downstream of an effluent discharge, the EOF increased by one order of magnitude, e.g., 40.3 to 574 ng F L-1, along the Teltow Canal. From our target analytes, mostly short-chained perfluorinated carboxylic acids and sulfonates occur in the water, which however makes up less than 10% of the EOF. The increase in EOF in the Teltow Canal correlates well with the increase of perfluorohexanoic acid (PFHxA), indicating that PFHxA is characteristic for the discharged EOF but not responsible for the increase. Hence, it points to PFHxA precursor discharge. The study highlights that EOF screening using HR-CS-GFMAS is necessary to identify the full scale of pollution with regard to PFAS and other organofluorines such as pharmaceutical compounds from the effluent of WWTPs.

Increasing temperature and flooding enhance arsenic release and biotransformations in Swiss soils.

Reductive dissolution is one of the main causes for arsenic (As) mobilisation in flooded soils while biomethylation and biovolatilisation are two microbial mechanisms that greatly influence the mobility and toxicity of As. Climate change results in more extreme weather events such as flooding and higher temperatures, potentially leading to an increase in As release and biotransformations. Here, we investigated the effects of flooding and temperature on As release, biomethylation and biovolatilisation from As-rich soils with different pH and source of As (one acidic and anthropogenic (Salanfe) and one neutral and geogenic (Liesberg)). Flooded soils incubated at 23 °C for two weeks showed a ~ 3-fold (Liesberg site) and ~ 7-fold (Salanfe site) increase in the total As concentration of soil solution compared to those incubated at 18 °C. Methyl- and thio-As species were found in the acidic soil and soil solution. High temperatures enhanced thiolation and methylation although inorganic As was predominant. We also show that volatile As fluxes increased more than 4-fold between treatments, from 18 ± 5 ng/kg/d at 18 °C to 75 ± 6 ng/kg/d at 23 °C from Salanfe soil. Our results suggest that high As soils with acidic pH can become an important source of As to the surrounding environment according to realistic climatic scenarios, and that biovolatilisation is very sensitive to increases in temperature. This study provides new data and further justifies further investigations into climate-induced changes on As release and speciation and its links to important factors such as microbial ecology and sulfate or iron biogeochemistry. SYNOPSIS: In the studied Swiss soils, elevated temperature increases arsenic mobility through volatilisation and methylation.

Mercury speciation in Scottish raptors reveals high proportions of inorganic mercury in Scottish golden eagles (Aquila chrysaetos): Potential occurrence of mercury selenide nanoparticles.

Knowledge of the uptake and fate of mercury (Hg) compounds in biota is important in understanding the global cycling of Hg and its transfer pathways through food chains. In this study, we analysed total mercury (T-Hg) and methylmercury (MeHg) concentrations in 117 livers of Scottish birds of prey that were found across Scotland and submitted for post-mortem examination through the Raptor Health Scotland project between 2009 and 2019. Statistical comparisons focussed on six species (barn owl, Tyto alba; Eurasian common buzzard, Buteo buteo; golden eagle, Aquila chrysaetos; hen harrier, Circus cyaneus; Eurasian sparrowhawk, Accipiter nisus; and tawny owl, Strix aluco) and showed that golden eagles had a statistically lower fraction of MeHg compared to other raptor species. Further investigation using stable carbon and stable nitrogen isotope ratio measurements carried out for the golden eagles (n = 15) indicated that the increased presence of inorganic mercury (iHg) correlated with a marine influence on the primarily terrestrial diet. Additional bioimaging (n = 1) with laser ablation - inductively coupled plasma - mass spectrometry indicated the co-location of Hg and selenium (Se) within the liver tissue and transmission electron microscopy showed evidence of nanoparticles within the range of 10-20 nm. Further analysis using single particle - inductively coupled plasma - mass spectrometry (n = 4) confirmed the presence of Hg nanoparticles. Together, the evidence suggests the presence of mercury selenide (HgSe) nanoparticles in the liver of some golden eagles that, to our knowledge, has never been directly observed in terrestrial birds of prey. This study points to two alternative hypotheses: these golden eagles may be efficient at breaking down MeHg and form HgSe nanoparticles as a detoxification mechanism (as previously observed in cetaceans), or some golden eagles with elevated iHg may have accumulated these nanoparticles by foraging on stranded cetaceans or seabirds.

Correction: Spatiotemporal distribution and speciation of silver nanoparticles in the healing wound.

Correction for 'Spatiotemporal distribution and speciation of silver nanoparticles in the healing wound' by Marco Roman et al., Analyst, 2020, 145, 6456-6469, DOI: 10.1039/D0AN00607F.

Development of Mercury Analysis by NanoSIMS for the Localization of Mercury-Selenium Particles in Whale Liver.

Nanoscale secondary ion mass spectrometry (NanoSIMS) is a dynamic SIMS technique, which offers high spatial resolution allowing the mapping of chemical elements at the nanometer scale combined with high sensitivity. However, SIMS for mercury analysis is a challenging issue due to the low secondary ion yield and has never been done on NanoSIMS. The introduction of an rf plasma oxygen primary ion source on NanoSIMS enabled higher lateral resolution and higher sensitivity for electropositive elements such as most metals. In this paper, for the first time, mercury analysis by NanoSIMS was developed applying the new rf plasma O- ion source. All mercury isotopes could be detected as Hg+ secondary ions and the isotopic pattern corresponded to their natural isotopic abundances. Furthermore, Hg+ detection in HgSe nanocrystals has been investigated where polyatomic interferences from selenium clusters were identified and separated by high mass resolution (ΔM/M ≥ 3200). However, in the presence of selenium a strong matrix effect was observed, decreasing the Hg+ secondary ion yield. In addition, a detection of Se+ ions was possible, too. The newly developed method was successfully applied to nanoscale localization by chemical imaging of HgSe particles accumulated in the liver tissue of sperm whale (Physeter macrocephalus). This demonstrated the applicability of NanoSIMS not only for mercury detection in surface analysis but also for mercury mapping in biological samples.

Characterisation of selenium and tellurium nanoparticles produced by Aureobasidium pullulans using a multi-method approach.

Aureobasidium pullulans was grown in liquid culture media amended with selenite and tellurite and selenium (Se) and tellurium (Te) nanoparticles (NPs) were recovered after 30 d incubation. A separation method was applied to recover and characterise Se and Te NPs by asymmetric flow field flow fractionation (AF4) with online coupling to multi-angle light scattering (MALS), ultraviolet visible spectroscopy (UV-Vis), and inductively coupled plasma mass spectrometry (ICP-MS) detectors. Additional characterisation data was obtained from transmission electron microscopy (TEM), and dynamic light scattering (DLS). Solutions of 0.2% Novachem surfactant and 10 mM phosphate buffer were compared as mobile phases to investigate optimal AF4 separation and particle recovery using Se-NP as a model sample. 88% recovery was reported for 0.2% Novachem solution, compared with 50% recovery for phosphate buffer. Different crossflow (Cflow) rates were compared to further investigate optimum separation, with recoveries of 88% and 30% for Se-NPs, and 90% and 29% for Te-NPs for 3.5 mL min-1 and 2.5 mL min-1 respectively. Zeta-potential (ZP) data suggested higher stability for NP elution in Novachem solution, with increased stability attributed to minimised NP-membrane interaction due to PEGylation. Detection with MALS showed monodisperse Se-NPs (45-90 nm) and polydisperse Te-NPs (5-65 nm).Single particle ICP-MS showed mean particle diameters of 49.7 ±â€¯2.7 nm, and 135 ±â€¯4.3 nm, and limit of size detection (LOSD) of 20 nm and 45 nm for Se-NPs and Te-NPs respectively. TEM images of Se-NPs and Te-NPs displayed a spherical morphology, with the Te-NPs showing a clustered arrangement, which suggested electrostatic attraction amongst neighbouring particles. Particle hydrodynamic diameters (dH) measured with dynamic light scattering (DLS) further suggested monodisperse Se-NPs and polydisperse Te-NPs distributions, showing good agreement with AF4-MALS for Se-NPs, but suggests that the Rg obtained from AF4-MALS for Te-NP was unreliable. The results demonstrate a complementary application of asymmetric flow field-flow fractionation (AF4), ICP-MS, light scattering, UV-Vis detection, and microscopic techniques to characterise biogenic Se and Te NPs.

The use of microwave-induced plasma optical emission spectrometry for fluorine determination and its application to tea infusions.

This study presents a novel method for fluorine quantification determination by microwave-induced plasma optical emission spectrometry (MIP-OES). Due to the low temperature of this plasma, atomic emission of fluorine could not be measured, instead CaF molecular emissions were measured by using a calcium solution mixed in the spray chamber with the sample using a T-piece. Several wavelengths were studied to find the best signal to noise ratio for fluorine determination and 530.45 nm was chosen. The limit of detection for the determination of fluorine via CaF using MIP-OES was 1.1 mg L-1. A linear response was observed over two orders of magnitude (R2 = 0.998). The developed method was applied to ten tea infusion samples from the UK and Saudi Arabia. The results were not significantly different (paired Student's t-test, p = 0.97) to the results obtained using the reference method, high-resolution continuum source graphite furnace molecular absorption spectrometry (HR-GF MAS). The total fluorine in the tea infusions varied between 2.7 and 7.8 mg L-1; all of which were above the WHO recommended level of fluoride (0.8-1.5 mg L-1) in drinking water. This method can potentially be used for total fluorine determination and might be useful for fluorine speciation analysis when coupled with HPLC.

Spatiotemporal distribution and speciation of silver nanoparticles in the healing wound.

The medical application of nanomaterials is growing fast. Amongst the most widely used, silver nanoparticles are antimicrobial agents whose key application is the care of burns and chronic wounds. Still, their absorption, distribution, metabolism and excretion behaviour in vivo has not yet been systematically investigated. We collected full-profile specimens of skin from four hospital patients with mid-to-deep thickness burns or equivalent skin wounds, treated with dressings containing silver nanoparticles or silver sulfadiazine. Synchrotron radiation µXRF/µXANES and laser ablation-ICP-MS were used to provide the first semi-quantitative/high resolution direct information on the spatiotemporal distribution and speciation of silver in vivo. The metal was rapidly released onto the wound surface, followed by a significant structure-dependent penetration into the damaged tissues. This was accompanied by sequential processes of metallic silver dissolution, chloride complexation, change to metal-thiol protein complexes, and final mobilization into deeper skin layers towards the vascular networks. Complete local clearance of silver was observed after 12 days of treatment in the case of full healing. The results provide a complete insight into the dynamics of silver in real human wounds, and a new basis for the design of innovative silver nanomaterials with optimal antibacterial efficacy and minimized risk for the patient.

Multi trace element profiling in pathogenic and non-pathogenic fungi.

Maintaining appropriate levels of trace elements during infection of a host is essential for microbial pathogenicity. Here we compared the uptake of 10 trace elements from 3 commonly-used laboratory media by 3 pathogens, Candida albicans, Cryptococcus neoformans and Aspergillus fumigatus, and a model yeast, Saccharomyces cerevisiae. The trace element composition of the yeasts, C. albicans, C. neoformans and S. cerevisiae, grown in rich (YPD) medium, differed primarily in P, S, Fe, Zn and Co. Speciation analysis of the intracellular fraction, which indicates the size of the organic ligands with which trace elements are complexed, showed that the ligands for S were similar in the three fungi but there were significant differences in binding partners for Fe and Zn between C. neoformans and S.cerevisiae. The profile for Cu varied across the 3 yeast species. In a comparison of C. albicans and A. fumigatus hyphae, the former showed higher Fe, Cu, Zn and Mn, while A. fumigatus contained higher P, S Ca and Mo. Washing C. albicans cells with the cell-impermeable chelator, EGTA, depleted 50-90 % of cellular Ca, suggesting that a large proportion of this cation is stored in the cell wall. Treatment with the cell wall stressor, Calcofluor White (CFW), alone had little effect on the elemental profile whilst combined Ca + CFW stress resulted in high cellular Cu and very high Ca. Together our data enhance our understanding of trace element uptake by pathogenic fungi and provide evidence for the cell wall as an important storage organelle for Ca.