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An analytical method with broad applicability based on cold vapor generation high-resolution continuum source quartz tube atomic absorption spectrometry was developed and evaluated for the determination of total mercury in matrices with various complexities and compositions. Sample preparation for different matrices of food, environmental samples and (bio)polymeric materials and unified operating conditions for derivatization and measurement were evaluated. The method was validated according to established requirements (Eurachem Guide 2014, EC Decisions 657/2002; 333/2007; 836/2011 and Association of Official Analytical Chemists Guide - AOAC). Analytical versatility was checked on various samples of fish fillets, mushrooms, soil, water and water sediment, sludge from a wastewater treatment unit, and (bio)polymeric materials from waste recycled from food packaging, computers and garden tools. Under optimal conditions for cold vapor generation in a batch system, namely 3% (v/v) HCl as reaction medium for 5 mL aliquot samples and a volume of 3.5 mL 0.3% (m/v) NaBH4 stabilized in 0.2% (m/v) NaOH as derivatization reagent, the detection limit for Hg in terms of peak height measurement (n = 7 days) was in the range 0.064 ± 0.004 µg L-1 in water, 0.014 ± 0.001 mg kg-1 in environmental samples and 0.009 ± 0.001 mg kg-1 in (bio)polymeric materials. Overall recovery of Hg by analysis of certified reference materials was 102 ± 20% (k = 2) in food, soil, wastewater and water sediment, and polyethylene. Precision for the measurement of various real samples ranged between 4.2 and 15.0%. A performance study highlighted that the method was sensitive, free of non-spectral interference coming from the multielemental matrix and that it complied with the requirements for Hg determination set in EC Decisions and AOAC Guidelines at least for the more common matrices analyzed for social impact.

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This study presents for the first time the coupling between in-situ Diffusive Gradient in Thin-film (DGT) passive sampling technique and ex-situ small-sized instrumentation based on electrothermal vaporization capacitively coupled plasma microtorch optical emission spectrometry (SSETV-µCCP-OES) for the simultaneous determination of Cd, Pb, Cu, Zn and Hg in surface water. Unique features of the DGT-SSETV-µCCP-OES are low power and low Ar consumption for plasma generation (15 W, 150 mL min-1) and significant improvement of the detection limits following DGT passive sampling. The new method was validated in terms of river water analysis in comparison with graphite furnace atomic absorption spectrometry and thermal decomposition atomic absorption spectrometry. Combining the abilities of preconcentration by in-situ Chelex-DGT passive sampling with plasma microtorch equipped with a low resolution microspectrometer provided multielemental simultaneous determination with detection limits of (µg L-1) 0.01 (Cd, Zn and Hg), 0.02 (Cu) and 0.07 (Pb) in water, at least one order of magnitude better than using grab sampling without preconcentration. It was possible the quantification of labile fraction of priority hazardous metals (Cd, Pb) in river water below the instrumental limits of detection (µg L-1) of 0.12 and 0.80 obtained in SSETV-µCCP-OES without DGT sampling. The precision of the method was in the range 15.3-22.4% (combined uncertainty), while the accuracy was 95-103% and trueness of 27-33% (expanded uncertainty, k = 2). The DGT-SSETV-µCCP-OES coupling proved to be an ideal and powerful tool for surface water analysis in compliance with green and white analytical chemistry concepts. The application of the RGB-12 algorithm provided very good red/green (AGREEprep)/blue/white scores (%) of 100/80/98/93, determined primarily by in-situ DGT passive sampling, very good detection limits and cost-effective SSETV-µCCP-OES instrumentation.

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A unified analytical method applicable to common foodstuff matrices was developed and characterized for total and inorganic arsenic determination by hydride generation high-resolution continuum source quartz tube atomic absorption spectrometry, which was established based on different sample preparation procedures. This new method was found to be interference-free and cost-effective in terms of reagents consumption for sample preparation and derivatization to arsine for the inorganic arsenic fraction. Microwave-assisted digestion in HNO3-H2O2 for total arsenic and extraction in 0.28 mol L-1 HNO3 by mechanical stirring in a water bath or ultrasound-assisted extraction in 0.01 mol L-1 HCl without separation of inorganic As, all coupled with arsine generation in 0.01 mol L-1 HCl medium with 0.6% NaBH4 in 0.01% NaOH in the presence of 0.2% L-cysteine was found to be suitable for all matrices. The results were statistically compared by applying Tukey's and Dunnett's multiple comparison methods (p > 0.05). The use of external calibration with As(III) standards and standard addition method for quantification showed the lack of non-spectral interferences from the multimineral matrices, resulting in a reliable method for total/inorganic As determination in various foodstuffs. The limits of detection for total/inorganic As using peak height measurement were 0.0044 ± 0.0005/0.0022 ± 0.0003 mg kg-1 (n = 25 days). The overall recovery for total/inorganic As in the certified reference materials was in the range of 98% ± 22%, and 99% ± 24% (k = 2). The extraction of inorganic As in 0.01 mol L-1 HCl and 0.28 mol L-1 HNO3 provided the recovery of 106% ± 25% and 100% ± 25% (k = 2), which was better than in 10 mol L-1 HCl. The precision of measurements in real samples of fish muscle, meat and organs, rice and rice-based baby foods with contents of 0.052-5.29 mg kg-1 total As and 0.005-0.063 mg kg-1 inorganic As was 9.8-18.8% and 8.7-32.0%, respectively, which was calculated based on the combined uncertainty.

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Here, we report synthesis and investigations of bulk and nano-sized La(0.7-x)EuxBa0.3MnO3 (x ≤ 0.4) compounds. The study presents a comparison between the structural and magnetic properties of the nano- and polycrystalline manganites La(0.7-x)EuxBa0.3MnO3, which are potential magnetocaloric materials to be used in domestic magnetic refrigeration close to room temperature. The parent compound, La0.7Ba0.3MnO3, has Curie temperature TC = 340 K. The magnetocaloric effect is at its maximum around TC. To reduce this temperature below 300 K, we partially replaced the La ions with Eu ions. A solid-state reaction was used to prepare bulk polycrystalline materials, and a sol-gel method was used for the nanoparticles. X-ray diffraction was used for the structural characterization of the compounds. Transmission electron spectroscopy (TEM) evidenced nanoparticle sizes in the range of 40-80 nm. Iodometry and inductively coupled plasma optical emission spectrometry (ICP-OES) was used to investigate the oxygen content of the studied compounds. Critical exponents were calculated for all samples, with bulk samples being governed by tricritical mean field model and nanocrystalline samples governed by the 3D Heisenberg model. The bulk sample with x = 0.05 shows room temperature phase transition TC = 297 K, which decreases with increasing x for the other samples. All nano-sized compounds show lower TC values compared to the same bulk samples. The magnetocaloric effect in bulk samples revealed a greater magnetic entropy change in a relatively narrow temperature range, while nanoparticles show lower values, but in a temperature range several times larger. The relative cooling power for bulk and nano-sized samples exhibit approximately equal values for the same substitution level, and this fact can substantially contribute to applications in magnetic refrigeration near room temperature. By combining the magnetic properties of the nano- and polycrystalline manganites, better magnetocaloric materials can be obtained.

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To provide new information on potential health benefits of dried fruits, the effects of in vitro digestion on minerals, total phenolics, total sugars and the antioxidant capacities were evaluated. For the first time, the bioaccessibility of these compounds during in vitro digestion was assessed by multivariate statistical analysis. Although the amount of all minerals decreased after digestion, moderate bioaccessibility was found, excepting Zn. The highest bioaccessibility of phenolics was obtained in prunes and the lowest in dates and cranberries. Total sugars content increased after in vitro digestion of dates, raisins and coconut, but decreased for cranberries, prunes and banana. The in vitro digestion led to an increase in the antioxidant capacity for the majority of dried fruits. The similarities/dis-similarities in pattern of analyzed parameters during digestion was revealed by heat map. Two-way joining cluster and principal component analysis were used to highlight the most relevant parameters in each digestion phase.

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The aim of the study was to develop the hydrogeochemical profiling of caves based on the elemental composition of water and silty soil samples and a multivariate statistical analysis. Major and trace elements, including rare earths, were determined in the water and soil samples. The general characteristics of water, anions content, inorganic and organic carbon fractions and nitrogen species (NO3- and NH4+) were also considered. The ANOVA-principal component analysis (PCA) and two-way joining analysis were applied on samples collected from Cloșani Cave, Romania. The ANOVA-PCA revealed that the hydrogeochemical characteristics of Ca2+-HCO3- water facies were described by five factors, the strongest being associated with water-carbonate rock interactions and the occurrence of Ca, Mg and HCO3- (43.4%). Although organic carbon fractions have a lower influence (20.1%) than inorganic ones on water characteristics, they are involved in the chemical processes of nitrogen and of the elements involved in redox processes (Fe, Mn, Cr and Sn). The seasonal variability of water characteristics, especially during the spring, was observed. The variability of silty soil samples was described by four principal components, the strongest influence being attributed to rare earth elements (52.2%). The ANOVA-PCA provided deeper information compared to Gibbs and Piper diagrams and the correlation analysis.

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Filamentous fungi native to heavy metals (HMs) contaminated sites have great potential for bioremediation, yet are still often underexploited. This research aimed to assess the HMs resistance and Hg remediation capacity of fungi isolated from the rhizosphere of plants resident on highly Hg-contaminated substrate. Analysis of Hg, Pb, Cu, Zn, and Cd concentrations by X-ray spectrometry generated the ecological risk of the rhizosphere soil. A total of 32 HM-resistant fungal isolates were molecularly identified. Their resistance spectrum for the investigated elements was characterized by tolerance indices (TIs) and minimum inhibitory concentrations (MICs). Clustering analysis of TIs was coupled with isolates' phylogeny to evaluate HMs resistance patterns. The bioremediation potential of five isolates' live biomasses, in 100 mg/L Hg2+ aqueous solution over 48 h at 120 r/min, was quantified by atomic absorption spectrometry. New species or genera that were previously unrelated to Hg-contaminated substrates were identified. Ascomycota representatives were common, diverse, and exhibited varied HMs resistance spectra, especially towards the elements with ecological risk, in contrast to Mucoromycota-recovered isolates. HMs resistance patterns were similar within phylogenetically related clades, although isolate specific resistance occurred. Cladosporium sp., Didymella glomerata, Fusarium oxysporum, Phoma costaricensis, and Sarocladium kiliense isolates displayed very high MIC (mg/L) for Hg (140-200), in addition to Pb (1568), Cu (381), Zn (2092-2353), or Cd (337). The Hg biosorption capacity of these highly Hg-resistant species ranged from 33.8 to 54.9 mg/g dry weight, with a removal capacity from 47% to 97%. Thus, the fungi identified herein showed great potential as bioremediators for highly Hg-contaminated aqueous substrates.

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The simultaneous determination of chemical vapor-generating elements involving derivatization is difficult even by inductively coupled plasma optical emission spectrometry or mass spectrometry. This study proposes a new direct liquid microsampling method for the simultaneous determination of As, Bi, Se, Te, Hg, Pb, and Sn, using a fully miniaturized set-up based on electrothermal vaporization capacitively coupled plasma microtorch optical emission spectrometry. The method is cost-effective, free from non-spectral interference, and easy to run by avoiding derivatization. The method involves the vaporization of analytes from the 10 µL sample and recording of episodic spectra generated in low-power (15 W) and low-Ar consumption (150 mL min-1) plasma microtorch interfaced with low-resolution microspectrometers. Selective vaporization at 1300 °C ensured the avoidance of non-spectral effects and allowed the use of external calibration. Several spectral lines for each element even in the range 180-210 nm could be selected. Generally, this spectral range is examined with large-scale instrumentation. Even in the absence of derivatization, the obtained detection limits were low (0.02-0.75 mg kg-1) and allowed analysis of environmental samples, such as cave and river sediments. The recovery was in the range of 86-116%, and the accuracy was better than 10%. The method is of general interest and could be implemented on any miniaturized or classical laboratory spectrometric instrumentation.

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A non-chromatographic method based on double liquid-liquid extraction and measurements by UV photochemical vapor generation capacitively coupled plasma microtorch optical emission spectrometry was developed and characterized for methylmercury determination in seafood. Samples were prepared following the procedure recommended in JRC Technical Report of European Commission formerly proposed for the determination of methylmercury in seafood by thermal decomposition atomic absorption spectrometry, namely confinement of Hg species in 47% HBr solution, extraction of CH3Hg+ in toluene and back-extraction in 1% l-cysteine aqueous solution. Mercury cold vapor was generated by flow injection UV photo-reduction from CH3Hg+ in 0.6molL-1 HCOOH, while quantification was performed against external Hg2+ aqueous standards and measuring Hg 253.652nm emission using a low power/Ar consumption plasma microtorch (15W, 100mLmin-1) and a low resolution microspectrometer (Ocean Optics). The figures of merit and analytical capability were assessed by analyzing certified reference materials and test samples of fish fillet and discussed in relation with requirements for Hg determination in seafood in European legislation (Decisions 2007/333/EC and 2002/657/EC) as well as compared to performances achieved in thermal decomposition atomic absorption spectrometry. The limit of detection and quantification of 2µgkg-1 and 6µgkg-1 respectively, precision of 2.7-9.4% and accuracy of 99±8% of the proposed method for the determination of CH3Hg+ fulfill the demands of European legislation for Hg quantification. The limit of detection and quantification were better than those in the used reference method or other non-/chromatographic methods taken for comparison. The analysis of certified reference materials and the Bland and Altman test performed on 12 test samples confirmed trueness of the proposed method and its reliability for the determination of traces of CH3Hg+ with 95% confidence level. The proposed method fulfills several demands of the eco-scale concept, is sensitive, simple and safe related to sample preparation through elimination of classical, harmful reductants and attractive by using economical miniaturized instrumentation incorporating a low power and low Ar consumption plasma.

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