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The aim of the study was to verify in a cardio-oncological model experiment if conjugated linoleic acids (CLA) fed to rats with mammary tumors affect the content of selected macro- and microelements in their myocardium. The diet of Sprague-Dawley females was supplemented either with CLA isomers or with safflower oil. In hearts of rats suffering from breast cancer, selected elements were analyzed with a quadrupole mass spectrometer with inductively coupled plasma ionization (ICP-MS). In order to better understand the data trends, cluster analysis, principal component analysis and linear discriminant analysis were applied. Mammary tumors influenced macro- and microelements content in the myocardium to a greater extent than applied diet supplementation. Significant influences of diet ( p = 0.0192), mammary tumors ( p = 0.0200) and interactions of both factors ( p = 0.0151) were documented in terms of Fe content. CLA significantly decreased the contents of Cu and Mn ( p = 0.0158 and p = 0.0265, respectively). The level of Ni was significantly higher ( p = 0.0073), which was more pronounced in groups supplemented with CLA. The obtained results confirmed antioxidant properties of CLA and the relationship with Se deposition. Chemometric techniques distinctly showed that the coexisting pathological process induced differences to the greater extent than diet supplementation in the elemental content in the myocardium, which may impinge on cardiac tissue's susceptibility to injuries.

Selenomethionine (SeMet) is one of the main selenium forms in foods and supplements. Determining its presence in natural food samples creates difficulties due to possible oxidation processes. The objective of this study was to evaluate the possible degradation of SeMet in water extracts of green teas, one of the most consumed beverages worldwide. Such a medium has not been investigated at this time. The HILIC-HPLC MS/MS method with different stationary phases was used to achieve the satisfactory separation of SeMet and selenomethionine oxide (SeMetO). The addition of dithiothreitol and β-mercaptoethanol, recommended to ensure that SeMet is kept in the reduced form, was also evaluated. The best separation was achieved using the zwitterionic HILIC stationary phase coupled to mass spectrometry and MeOH with water (85/15, v / v ) as the eluent. Extraction was done with hot water with the addition of β-mercaptoethanol. The infusions prepared from Lung-Ching teas (from the Zhejiang Province in China) contained the highest concentration of selenium in a typical cup of tea (12.5-17.3 µg L -1 ). For other tested teas it decreased in the following order: Yunnan > Dilmah > Lipton. For Lung-Ching teas, the sum of concentrations of SeMet and SeMetO corresponded to about 46-63% of the total selenium in their extracts.

A green vortex assisted based liquid-liquid microextraction (VA-LLME) method was developed for preconcentration of selenium. Ammonium pyrrolidine dithiocarbamate (APDC) was used to form a hydrophobic complex with selenium in natural water, agricultural soil and food samples by GFAAS. Whereas Triton X-114, a nonionic surfactant and 1-butyl-3-methylimidazolium hexafluorophosphate ionic liquid were used for Se extraction as a dispersing medium. The conical flasks contents were shack on a vortex mixer to increase the extraction efficiency. Multivariate techniques were used to evaluate extraction parameters; pH, vortex time, APDC amount, volume of ionic liquid and Triton X-114 and centrifugation rate on the recovery of Se. The central composite design (CCD) was used for further optimization of the essential extraction parameters. The enhancement factor and limit of detection were obtained as 98.7 and 0.07 µg L -1 . The certified reference materials was used for accuracy of method and the related standard deviation was found to be 3.51%. The resulted data indicated that concentrations of Se in all types of water samples were below the permissible limit recommended by WHO., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

The development and application of new selenium-enriched polysaccharides has become a critical topic in recent years. In this study, a natural selenium-enriched polysaccharide fraction (Se-POP-21) produced by Pleurotus ostreatus was purified, characterized, and investigated the antioxidant and antitumor activities in vitro. The Se-POP-21 was mainly composed of mannose, glucose, galactose and arabinose, with a molar ratio of 18.01:2.40:26.15:7.34, of which molecular weight was 15,888 Da and the selenium content was 5.31 μg/g. Spectral analysis demonstrated that Se-POP-21 represented a non-triple helix pyranopolysaccharide and selenium occurred in the form of C-O-Se and SeO. Molecular size and morphology studies showed that Se-POP-21 exhibited a spherical shape with a particle size distribution between 100 and 200 nm, even though Se-POP-21 aggregates were also found with a size between 500 and 600 nm. In addition, Se-POP-21 showed strong scavenging capacity to DPPH and hydroxyl radical. More, cell experiments showed that Se-POP-21 could reduce viability of A549, SKOV3, HepG2 and MCF-7 cells, induce apoptosis and inhibit metastasis of A549 cells. A potential mechanism was that Se-POP-21 inhibited the epithelial-to-mesenchymal transition of cancer cells. Se-POP-21 featured no significant effect on normal cells. Se-POP-21 showed great potential to develop into a natural antioxidant or low-toxic antitumor drug., Competing Interests: Declaration of competing interest The authors declare no competing financial interest., (Copyright © 2020. Published by Elsevier B.V.)

In this study, a novel, easy, rapid and green zirconium nanoparticles (Zr-NPs) based dispersive solid phase extraction (DSPE) method is presented for the precise and sensitive determination of selenium by slotted quartz tube-flame atomic absorption spectrophotometry (SQT-FAAS). Influential parameters of the extraction procedure were optimized by altering one parameter while keeping the other parameters constant. The optimum conditions were selected as 10 mg of Zr-NPs, 75 s vortex period, and 200 µL of concentrated HCl for 30 mL of sample/standard solution. The linear range of the developed method was found to be between 25 and 100 µg/L, and the respective limits of detection and quantification were 5.3 and 18 µg/L. About 415 folds enhancement in detection power was achieved by the optimized method relative to the conventional FAAS. Green tea samples were spiked and used for recovery experiments and the results obtained were between 92 and 102%., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

The purpose of this research is to compare and enhance the antimicrobial and antibiofilm potentials of the biogenic selenium nanoparticles (Se NPs) produced by cost-effective and eco-friendly green methods. The synthesis of Se NPs is described in this manuscript by two different methods: a biogenic process using Penicillium chrysogenum filtrate and by utilizing gentamicin drug (CN) following the application of gamma irradiation. Se NPs were characterized by UV-Vis., HRTM, FTIR, XRD, DLS, SEM, and EDX mapping technique. Antimicrobial and antibiofilm activities of the synthesized Se NPs were investigated against multidrug-resistant (MDR) bacteria and yeast causing severe diseases such as urinary tract infection (UTI). The biogenic Se NPs exhibited an absorption peak at 435.0 nm while Se NPs-CN showed an absorption peak at 350.0 nm which is related to the surface plasmon resonance (SPR). Data obtained from HRTEM, SEM/mapping, and XRD analysis confirmed the mono-dispersion and crystalline nature of the prepared samples with an average diameter of 33.84 nm and 22.37 nm for the mycogenic Se NPs and Se NPs-CN, respectively. The synthesized Se NPs-CN possesses an encouraging antimicrobial potential with respect to the biogenic Se NPs against all examined UTI-causing microbes. Remarkably, Se NPs-CN showed antimicrobial potential toward Candida albicans with a zone of Inhibition (ZOI) recorded at 26.0 mm, 23.0 mm ZOI for Escherichia coli and 20.0 mm ZOI against Staphylococcus aureus. In addition, the incorporated Se NPs-CN displayed an enhanced percentage of biofilm inhibition of 88.67%, 87.93%, and 85.20% against S. aureus, P. aeruginosa, and E. coli, respectively. Accordingly, the novelty of the present research involves the green synthesis of mono-dispersed Se NPs and combining the synergistic potential of CN with Se NPs for potential biomedical, pharmaceutical, and therapeutic applications especially in the treatment of UTI. Graphical Abstract.

We hypothesized that selenium(Se)-enriched polysaccharides would possess superior biological activity when compared to those non-enriched. To verify this hypothesis, we obtained by biotechnological methods a Se-enriched analog of Japanese anticancer drug lentinan and, as a reference, the non-Se-enriched fraction. We tested the effects of the obtained fractions on the proliferation of human peripheral blood mononuclear cells. The results suggested a selective immunosuppressive activity, non-typical for mushroom derived polysaccharides. Both fractions caused significant inhibition of human T lymphocyte proliferation induced by mitogens, without significant effects on B lymphocytes. The inhibitory effect was not due to the toxicity of the examined polysaccharides. In normal (HUVEC) or malignant (HeLa) cells tested fractions significantly enhanced cell viability and protected the cells from oxidative stress conditions. However, we observed no effect of the polysaccharide fractions on the production of reactive oxygen species by granulocytes in vitro. The selenium content increased the biological activity of the tested polysaccharide fractions., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

A newly synthesized polystyrene-g-polyoleic acid-g-polyethylene glycol graft copolymer (PoleS-PEG) was used as adsorbent in the solid phase microextraction of selenium ions by using electrothermal atomic absorption spectrometry (ETAAS). Neodymium magnet was used for separation of analyte ions. Various analytical parameters such as pH, adsorbent amount, mixing time, eluent solution, sample volume, etc. were optimized. The matrix effects of some cations and anions were also studied. The capacity of the adsorbent was found 11.5 mg g -1 . The preconcentration factor was found to be 50. The detection limit (LOD) and quantification limit (LOQ) were found 6.06 ng L -1 and 20 ng L -1 , respectively. The calibration curve was linear in the range of 0.02-4.0 μg L -1 . Relative standard deviation was found 3.2%. The accuracy of the method was provided by using standard reference materials. The optimized method was successfully applied to natural water and food samples., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

The removal of selenium from superficial and waste water is a worldwide problem. The maximum limit according to the World Health Organization (WHO) for the selenium in the water is set at a concentration of 10 μg/L. Carbon based adsorbents have attracted much attention and recently demonstrated promising performance in removal of selenium. In this work, several materials (iron oxide based microparticles and graphene oxides materials) and their composites were prepared to remove Se(IV) from water. The graphene oxides were prepared according to the simplified Hummer's method. In addition, the effect of pH, contact time and initial Se(IV) concentration was tested. An electrochemical method such as the differential pulse cathodic stripping voltammetry was used to determine the residual selenium concentration. From the experimental data, Langmuir adsorption model was used to calculate the maximum adsorption capacity. Graphene oxide particles modified by iron oxide based microparticles was the most promising material for the removal of Se(IV) from its aqueous solution at pH 2.0. Its adsorption efficiency reached more than 90% for a solution with given Se(IV) concentration, meanwhile its maximal recorded adsorption capacity was 18.69 mg/g., Competing Interests: The authors declare no conflict of interest.

In developing an algal treatment system, selenium (Se) removal efficiency by Chlorella vulgaris was evaluated under various conditions such as Se concentration, algal density, temperature and pH. A maximum removal efficiency plateau of ∼90% was observed between 1000-3000 μg Se/L while the tolerance of Se toxicity was found at 6000 μg Se/L. C. vulgaris of 0.75 g DW/L showed the highest removal efficiency (84%), and volatilization was dominant below 1.37 g DW/L. Se volatilization was two times higher at 25 °C than at 20 °C in the first 24 h. Moreover, the highest removal efficiency (77%) was obtained at pH 8.0, compared to 66.5% at pH 6.5 and 40% at pH 10.0. To prevent ecotoxicity, Se laden algae were further burned to ashes or filtered out by Anodonta woodiana. After burning, biomass Se was reduced by 99%, with organo-Se entirely converted into inorganic Se, lowering Se bioavailability. A. woodiana removed 54% of Se in 24 h, leading to Se bioaccumulation in soft tissues, which may serve as dietary Se supplements for human health. Our results suggest the cleanup of Se-contaminated water from either agricultural runoff or industrial discharge could be achieved using an algal treatment system with minimum potential ecotoxicity., (Copyright © 2018 Elsevier B.V. All rights reserved.)

In the present study the use of Selenium-fortified olive leaves as potential dietary source of Se in rabbit nutrition was evaluated. Sixty New Zealand White rabbits (35 days of age) were randomly assigned to the following dietary treatments: standard diet (C), and C supplemented with either 10% olive leaves (OL) or 10% Selenium-fortified olive leaves (SeOL; 100 mg/L of foliar spray sodium selenate solution). At 70 days of age, 10 rabbits per group were slaughtered and the oxidative status, mineral profile and Selenium speciation of Longissimus dorsi meat was analyzed. Meat of the SeOL group exhibited better oxidative status (lower TBARS, higher GPx and α-tocopherol values) and a 5-fold higher Se content compared to that of the other treatments. The main Se form was SeMet (7-fold higher in the SeOL group), followed by SeCys 2 . The present trial demonstrates the possibility of using agro-industrial by-products as ingredients in rabbit feeds, thereby enriching meat bioactive compound content., (Copyright © 2018 Elsevier GmbH. All rights reserved.)

Se-containing polysaccharide is known to Se-conjugated macromolecule, with potent bioactivities due to the synergistic effects of Se and native polysaccharide. It is not only explored as a novel Se source in dietary supplement, but also as the superb bioactive component owning various functions, including antioxidant, antitumor, immune-enhancement, hepatoprotective, antidiabetic, anti-inflammatory and neuroprotective activities. Se-containing polysaccharide can exert the efficacy of Se and polysaccharide, and its activities are much higher than those of Se or polysaccharide. In the last decades, numerous reports on Se-containing polysaccharide (including natural Se-containing polysaccharide and selenylated polysaccharide) appeared in literature. For the first time, this article systematically introduces recent advances on preparation, structural characterization and bioactivities of Se-containing polysaccharide in details, and discusses its future prospects and the weaknesses in the current study., (Copyright © 2018. Published by Elsevier B.V.)

Nanoparticles (NPs) are gaining special interest due to their recent applications as antimicrobial agents to defeat the massive threat of resistant pathogens. This study focused on the utilisation of Streptomyces isolate S12 purified from waste discharge soil in the biological synthesis of silver (Ag), selenium (Se), and zinc oxide (ZnO) NPs. The isolate S12 was related to Streptomyces enissocaesilis according to 16S rRNA sequence analysis, morphological characteristics, and biochemical reactions. The cell-free supernatant has been used for the synthesis of Ag, Se, and ZnO NPs. The synthesised NPs were characterised using ultraviolet-visible spectroscopy, dynamic light scattering (DLS), transmission electron microscopy, and Fourier transform infrared spectroscopy. The biogenic NPs were evaluated for antimicrobial effects against different Gram-positive and Gram-negative resistant isolates using the broth microdilution method. They showed antibacterial effect against standard and resistant isolates; Bacillus cereus , Staphylococcus aureus ATCC 29213, S. aureus S1.1, methicillin resistant S. aureus (MRSA 303, 402 and 807), Escherichia coli ATCC 12435, E. coli E7, Klebsiella pneumoniae ATCC 51503, K. pneumoniae K5, K112, Pseudomonas aeruginosa PAO1, and P. aeruginosa P8. This study showed the green synthesis of various NPs using Streptomyces isolate S12 which demonstrated diverse activities against multi-drug resistant isolates.

Selenium (Se) is an essential element for animals, including fish. Due to changes in feed composition for Atlantic salmon (Salmo salar), it may be necessary to supplement feeds with Se. In the present work, the transfer of Se and Se species from feed to muscle of Atlantic salmon fed Se supplemented diets was studied. Salmon were fed basal fish feed (0.35 mg Se/kg and 0.89 mg Se/kg feed), or feed supplemented either with selenised yeast or sodium selenite, at low (1-2 mg Se/kg feed) and high (15 mg Se/kg feed) levels, for 12 weeks. For the extraction of Se species from fish muscle, enzymatic cleavage with protease type XIV was applied. The extraction methods for Se species from fish feed were optimised, and two separate extraction procedures were applied, 1) enzymatic cleavage for organic Se supplemented feeds and 2) weak alkaline solvent for inorganic Se supplemented feeds, respectively. For selenium speciation analysis in feed and muscle tissue anion-exchange HPLC-ICP-MS for analysis of inorganic Se species and cation-exchange HPLC-ICP-MS for analysis of organic Se species, were applied. In addition, reversed phase HPLC-ICP-MS was applied for analysis of selenocysteine (SeCys) in selected muscle samples. The results demonstrated that supplemented Se (organic and inorganic) accumulated in muscle of Atlantic salmon, and a higher retention of Se was seen in the muscle of salmon fed organic Se diets. Selenomethionine (SeMet) was the major Se species in salmon fed basal diets and diets supplemented with organic Se, accounting for 91-118% of the total Se. In contrast, for muscle of salmon fed high inorganic Se diet, SeMet accounted for 30% of the total Se peaks detected. Several unidentified Se peaks were detected, in the fish fed high inorganic diet, and analysis showed indicated SeCys is a minor Se species present in this fish muscle tissue., (Copyright © 2018 The Authors. Published by Elsevier GmbH.. All rights reserved.)

Selenium (Se) is an important micronutrient but also a strong toxin with a narrow tolerance range for many organisms. As such, a globally heterogeneous Se distribution in soils is responsible for various disease patterns (i.e. Se excess and deficiency) and environmental problems, whereby plants play a key role for the Se entrance into the biosphere. Selenium isotope variations were proved to be a powerful tracer for redox processes and are therefore promising for the exploration of the species dependent Se metabolism in plants and the Se cycling within the Critical Zone. Plant cultivation setups enable systematic controlled investigations, but samples derived from them-plant tissue and phytoagar-are particularly challenging and require specific preparation and purification steps to ensure precise and valid Se isotope analytics performed with HG-MC-ICP-MS. In this study, different methods for the entire process from solid tissue preparation to Se isotope measurements were tested, optimized and validated. A particular microwave digestion procedure for plant tissue and a vacuum filtration method for phytoagar led to full Se recoveries, whereby unfavorable organic residues were reduced to a minimum. Three purification methods predominantly described in the literature were systematically tested with pure Se solution, high concentrated multi-element standard solution as well as plant and phytoagar as target matrices. All these methods efficiently remove critical matrix elements, but differ in Se recovery and organic residues. Validation tests doping Se-free plant material and phytoagar with a reference material of known Se isotope composition revealed the high impact of organic residues on the accuracy of MC-ICP-MS measurements. Only the purification method with no detectable organic residues, hydride generation and trapping, results in valid mass bias correction for plant samples with an average deviation to true δ82/76Se values of 0.2 ‰ and a reproducibility (2 SD) of ± 0.2 ‰. For phytoagar this test yields a higher deviation of 1.1 ‰ from the true value and a 2 SD of ± 0.1 ‰. The application of the developed methods to cultivated plants shows sufficient accuracy and precision and is a promising approach to resolve plant internal Se isotope fractionations, for which respective δ82/76Se values of +2.3 to +3.5 ‰ for selenate and +1.2 to +1.9 ‰ for selenite were obtained.

In this study, the removal and reduction of selenite [Se(IV)] by growing Aspergillus sp. J2 were investigated. The lag phase, growth rate and biomass of J2 was not significantly influenced by the presence of 100 mg/L Se(IV). A rapid Se(IV) removal process took place from the 3rd to the 4th day during the growth of J2. Scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy and X-ray diffraction analyses showed that the Se(IV) did not cause any visible effects on cell morphology and the reduced amorphous elemental selenium [Se(0)] nanoparticles were mainly on the surface of the mycelial cell walls. The macromolecules containing amine groups also interact with Se(IV) and could play an important role in Se(IV) removal by J2.

A highly sensitive method was developed for the simultaneous separation and determination of organic and inorganic selenium species in rice by ion-pairing reversed-phase chromatography combined with inductively coupled plasma tandem mass spectrometry. To achieve a good separation of these species, a comparison between anion-exchange chromatography and ion-pairing reversed-phase chromatography was performed. The results indicated that ion-pairing reversed-phase chromatography was more suitable due to better separation and higher sensitivity for all analytes. In this case, a StableBond C18 column proved to be more robust or to have a better resolution than other C18 columns, when 0.5 mM tetrabutylammonium hydroxide and 10 mM ammonium acetate at pH 5.5 were used as the mobile phase. Moreover, an excellent sensitivity was obtained in terms of interferences by means of tandem mass spectrometry in the hydrogen mode. The detection limits were 0.02-0.12 μg/L, and recoveries of five selenium species were 75-114%, with relative standard deviations ≤ 9.4%. This method was successfully applied to the analysis of rice samples. Compared with previous studies, the proposed method not only gave comparable results when used for measuring selenium-enriched rice, but it can provide greater sensitivity for the detection of low concentrations of selenium species in rice., (© 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Studies have shown that information related to the presence of low-molecular-weight metabolites is frequently lost after deproteinization of complex matrices, such as blood and plasma, during sample preparation. Therefore, the effect of several deproteinization reagents on low-molecular-weight selenium species has been compared by species-specific isotope labeling. Two isotopically enriched selenium tracers were used to mimic models of small inorganic anionic ( 77 Se-selenite) and organic zwitterionic ( 76 Se-selenomethionine) species. The results presented here show that the use of a methanol-acetonitrile-acetone (1:1:1 v/v/v) mixture provided approximately two times less tracer loss from plasma samples in comparison with the classic procedure using acetonitrile, which may not be optimal as it leads to important losses of low-molecular-weight selenium species. In addition, the possible interactions between selenium tracers and proteins were investigated, revealing that both coprecipitation phenomena and association with proteins were potentially responsible for selenite tracer losses during protein precipitation in blood samples. However, coprecipitation phenomena were found to be fully responsible for losses of both tracers observed in plasma samples and of the selenomethionine tracer in blood samples. This successfully applied strategy is anticipated to be useful for more extensive future studies in selenometabolomics., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Wetland mesocosms were constructed to assess two hybrid poplar clones (Populustrichocarpa×P. deltoides×P. nigra '345-1' and '347-14') for treating saline water high in boron (B) and selenium (Se), and a hydroponic experiment was performed to test the B tolerance and B accumulation in both clones. In the mesocosm experiment, clone 345-1 exhibited no toxic symptoms at an EC of 10mScm -1 , while clone 347-14 showed slight toxic symptoms at 7.5mScm -1 . The removal percentages of B, Se, sodium (Na), and chloride (Cl) ranged from 26.7-45.6%, 50-69.4%, 18.4-24.0%, and 15.8-23.2%, respectively, by clone 345-1, and from 22.9-29.4%, 31.7-43.8%, 16.5-24.2%, and 14.9-23.9%, respectively, by clone 347-1. In the hydroponic experiment, B toxic symptoms were observed at treatments of 150 and 200mg B L -1 for clones 345-1 and 347-14, respectively. The greatest leaf B concentrations of 3699 and 1913mgkg -1 were found in clone 345-1 and clone 347-14, respectively. The translocation factor (TF) of clone 347-14 was less than clone 345-1. Clone 345-1 only showed significantly greater (P<0.05) B removal percentages than clone 347-14 when B treatment was <20mg B L -1 . In conclusion, both tested poplar clones competitively accumulated and removed B and Se in constructed wetlands., (Copyright © 2017. Published by Elsevier B.V.)

Natural organic matter (NOM) can have a significant influence on the mobility and fate of inorganic oxyanions, such as arsenic and selenium, in the environment. There is evidence to suggest that interactions between NOM and these oxyanions are facilitated by bridging cations (primarily Fe 3+ ) through the formation of ternary complexes. Building on previous work characterizing ternary complexes formed in the laboratory using purified NOM, this study describes the extraction and characterization of intact ternary complexes directly from a soil matrix. The complexes are stable to the basic extraction conditions (pH 12) and do not appear to change when the pH of the extract is adjusted back to neutral. The results suggest that ternary complexes between NOM, cations, and inorganic oxyanions exist in natural soils and could play a role in the speciation of inorganic oxyanions in environmental matrices., (Published by Elsevier Ltd.)

Microbial reduction of selenium sulfide (SeS 2 ) is a key step in a new treatment process to recover selenium from selenate and selenite streams. In this process, selenate is first reduced to selenite, and subsequently selenite is reduced by sulfide and precipitates from the solution as SeS 2 . The latter is bio-reduced to elemental selenium and sulfide. Two anaerobic granular sludges (Eerbeek and Emmtec) were tested for their efficiency to reduce commercial crystalline SeS 2 . Emmtec sludge had the highest reducing capacity with commercial SeS 2 and was therefore also used for the bioreduction of laboratory synthesized amorphous SeS 2 . Synthesized SeS 2 was formed mixing a sulfide solution and effluent containing selenite. With both SeS 2 solids (commercial and synthesized SeS 2 ), Emmtec sludge produced sulfide and a solid consisting of hexagonal elemental selenium. The crystalline hexagonal structure suggests the absence of biomolecules, which stabilize amorphous selenium bio-particles under comparable process conditions (T=30°C and a pH between 6 and 7). Selenium particles were not attached to the biomass, suggesting an extracellular formation. The results support the feasibility of the bio-reduction process using sulfur for recovering selenium from water., (Copyright © 2017 Elsevier B.V. All rights reserved.)

A selenium (Se)-containing polysaccharide, lotus leaf selenium (Se)-polysaccharide (LLP), was isolated from a lotus leaf. The effects of LLP on antioxidant enzyme activities and insulin resistance in pregnant rats with gestational diabetes mellitus (GDM) were investigated. LLP administered orally at two doses (50 and 100 mg/kg) could significantly reverse the weight loss of pregnant rats before the delivery, fetal rats, and placentas in GDM rats (P < 0.05). Furthermore, LLP treatment induced a decrease of fasting blood glucose (FBG) and fasting blood insulin (FINS) levels in GDM rats, but an increase of hepatic glycogen content, when compared with those in GDM rats (P < 0.05). Also, oral administrations of LLP markedly improved the lipid profile of GDM rats, as evidenced by a reduction of total cholesterol (TC), triglyceride (TG), and low-density lipoprotein (LDL) cholesterol levels except for the high-density lipoprotein (HDL) cholesterol level. Additionally, antioxidant enzyme levels, such as superoxide dismutase (SOD), catalase, glutathione peroxidase (GPx), and glutathione (GSH), in liver tissues of the GDM group were lower than those of the other groups, and following treatment of LLP, these indexes in liver tissues were equivalent to those of the control group (P > 0.05). All the data indicated that LLP may be a promising drug candidate or a healthcare food for GDM therapy or protection.

Wastewaters contaminated by both selenium and ammonium need to be treated prior to discharge into natural water bodies, but there are no studies on the simultaneous removal of selenium and ammonium. A sequencing batch reactor (SBR) was inoculated with activated sludge and operated for 90days. The highest ammonium removal efficiency achieved was 98%, while the total nitrogen removal was 75%. Nearly a complete chemical oxygen demand removal efficiency was attained after 16days of operation, whereas complete selenate removal was achieved only after 66days. The highest total Se removal efficiency was 97%. Batch experiments showed that the total Se in the aqueous phase decreased by 21% with increasing initial ammonium concentration from 50 to 100mgL -1 . This study showed that SBR can remove both selenate and ammonium via, respectively, bioreduction and partial nitrification-denitrification and thus offer possibilities for treating selenium and ammonium contaminated effluents., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Different ionic liquids (ILs) were assayed as mobile phase modifiers for the separation and determination of selenite [Se(IV)], selenate [Se(VI)], selenomethionine (SeMet) and Se-methylselenocysteine (SeMeSeCys) by reversed-phase high-performance liquid chromatography coupled to hydride generation atomic fluorescence spectrometry (RP-HPLC-HG-AFS). The use of several ILs: 1-butyl-3-methylimidazolium chloride, 1-hexyl-3-methylimidazolium chloride ([C 6 mim]Cl), 1-octyl-3-methylimidazolium chloride, 1-dodecyl-3-methylimidazolium bromide, 1-hexadecyl-3-methylimidazolium bromide and tributyl(methyl)phosphonium methylsulphate was evaluated. Also, the effect of pH, buffer type and IL concentration on the separation of Se species was studied. Complete separation was attained within 12min using a C 8 column and a gradient performed with a mobile phase containing 0.1% (v/v) [C 6 mim]Cl at pH 6.0. The proposed method allows the separation of inorganic and organic Se species in a single chromatographic run, adding further benefits over already reported methods based on RP-HPLC. In addition, the influence of ILs on the AFS signals of each Se species was evaluated and a multivariate methodology was used for optimization of AFS sensitivity. The limits of detection were 0.92, 0.86, 1.41 and 1.19μgL -1 for Se(IV), Se(VI), SeMet and SeMeSeCys, respectively. The method was successfully applied for speciation analysis of Se in complex samples, such as wine, beer, yeast and garlic., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Effect of selenium-containing biocomposites obtained from submerged cultures of macrobasidiomycetes Ganoderma applantum, G. cattienensis, G. colossus G. lucidum, G. neojaponicum, and G. valesiacum, on plant pathogenic bacteria Clavibacter michiganensis ssp. sepedonicus (Cms), Micrococcus luteus, Pectobacterium atrosepticum, Pectobacterium carotovorum subsp. carotovorum, Pseudomonas fluorescens, Pseudomonas viridiflava, and Xanthomonas campestris was studied. Oxopropyl-4-hydroxychromenones were used as components of the fungal nutrient media. The bacteriostatic and bactericidal activity of the Se-containing and Sefree substances of fungal origin against plant pathogenic bacteria was determined using colony-forming units count, the agar well diffusion method, and by turbidity measurements of bacterial suspensions. The composites produced from the extracellular metabolites of G. cattienensis SIE1302 with 4-hydroxy-3-(3-oxo-1,3- diphenyl propyl)-chromen-2-one (S(45)), and of G. lucidum SIE1303 with 4-hydroxy-3-(3-oxo-1-(3-nitrophenyl)- 3-phenylpropyl)-chromen-2-one (S(NO2)) possessed the most pronounced antibacterial action against Cms. The composites produced from the isolates of G. valesiacum 120702 with S(NO2) showed the maximal antibacterial activity against Xanthomonas campestris B-610. High antimicrobial effect of G. lucidum 1315 with S(NO2) against Xanthomonas campestris B-610 and of G. colossus SIE1301 against Pseudomonas fluorescens EL-2.1 was revealed. The pioneering information on the biological activity of coumarin series compounds in their application for producing the substances of fungal origin was obtained.

Remediation of selenate (SeO4 (2-) ) contamination through microbial reduction is often challenging due to the presence of sulfate (SO4 (2-) ), which can lead to competition for the electron donor and the co-production of toxic H2 S. Microbial reduction of SeO4 (2-) in the presence of SO4 (2-) was studied in two hydrogen-based membrane biofilm reactors (MBfRs). One MBfR was initiated with SO4 (2-) -reducing conditions and gradually shifted to SeO4 (2-) reduction. The second MBfR was developed with a SeO4 (2-) -reducing biofilm, followed by SO4 (2-) introduction. Biofilms within both MBfRs achieved greater than 90% SeO4 (2-) reduction, even though the SeO4 (2-) concentration ranged from 1,000-11,000 μg/L, more than 20-200 times the maximum contaminant level for drinking water (50 μg/L). Biofilm microbial community composition, assessed by 16S rRNA gene-based amplicon pyrosequencing, was distinct between the two MBfRs and was framed by alterations in SeO4 (2-) loading. Specifically, high SeO4 (2-) loading resulted in communities mainly composed of denitrifying bacteria (e.g., Denitratisoma and Dechloromonas). In contrast, low loading led to mostly sulfate-reducing bacteria (i.e., Desulfovibrio) and sulfur-oxidizing bacteria (i.e., Sulfuricurvum and Sulfurovum). SeO4 (2-) was reduced to elemental selenium (Se°), which was visualized within the biofilm as crystalloid aggregates, with its fate corresponding to that of biofilm solids. In conclusion, microbial biofilm communities initiated under either SeO4 (2-) or SO4 (2-) -reducing conditions attained high SeO4 (2-) removal rates even though their microbial community composition was quite distinct. Biotechnol. Bioeng. 2016;113: 1736-1744. © 2016 Wiley Periodicals, Inc., (© 2016 Wiley Periodicals, Inc.)

FeOOH, a frequently used adsorbent, has been widely applied in purifying aqueous heavy metals, and its performance can be greatly improved by enlarging the number of surface active sites. To this end, we fabricated FeOOH hollow microboxes constructed from numerous 2D nanosheets via a template-engaged reaction between Prussian blue (PB) and NaOH solution. With combined observations from X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS), we confirmed that the hollow microboxes corroded from PB were composed of ample frizzy FeOOH nanosheets, which ensured extensive exposure of the surface active sites. Moreover, the FeOOH microboxes were utilized as an adsorbent in the removal of heavy metals (As(III), As(V) and Se(IV)) from water and the maximum adsorption capacities were reached up to 192.19 mg g(-1), 250.0 mg g(-1) and 169.9 mg g(-1) at pH = 7.0, 4.0 and 5.0, respectively. The superior adsorptive performance of the FeOOH microboxes was derived from their large content of reactive exposed hydroxyl groups, which was unambiguously confirmed by X-ray adsorption fine structure spectroscopy (XAFS), as well as by surface site density analysis.

Sprouts contain potent compounds which while influencing crucial transduction pathways in cell reveal anti-inflammatory and anticancer activities. In this study, we report the biological activity for seeds and colourful sprouts of four types of edible amaranth, as amaranth has recently attracted interest due to its appreciable nutritional value. MTT assay conducted for the amaranth seeds and sprouts did not show any adverse effect on the viability of murine RAW 264.7 cells. As amaranth accumulates selenium, the sprouts were supplemented with this trace element (10 mg/L; 15 mg/L Se as sodium selenite) while growing. Selenium concentration in sprouts was observed to be significantly correlated with betacyanins content of the tested species. The amounts of Se and betacyanins in sprouts varied for various Amaranth species. In the present study, Amaranthus cruentus sprouts with the highest betacyanins (19.30 ± 0.57-28.85 ± 2.23 mg of amaranthin/100 g of fresh weight) and high total selenium (22.51 ± 1.57-1044.75 ± 73.08 μg/L in methanol extracts) content prevented NFκB translocation to the cell nucleus and subsequently exerted an anti-inflammatory effect by significant decreasing inflammatory interleukin 6 production (587.3 ± 34.2-710.0 ± 88.1 pg/mL) in the cell culture of activated RAW 264.7 macrophages (vs LPS control 1520 ± 114 pg/mL).

The objective of this research was to test whether selenium-yeast (Se-yeast) is a better source of selenium than sodium selenite for accumulation in mycelia and immunoactive cell wall polysaccharides. Culture media were enriched in selenium to a concentration of 20 µg/mL. Selenium was added to the medium either in the form of sodium selenite or in form of Se-yeast (Sel-Plex; Alltech Inc., Lexington, KY). The total selenium concentrations in the mycelium biomass and in the isolated crude polysaccharides were determined using atomic absorption spectroscopy. We found that selenium accumulated more efficiently in cultures enriched with Se-yeast. A higher concentration of selenium was also found in the crude polysaccharide fractions isolated from the mycelium grown in Se-yeast-enriched media. With the use of the needle trap gas chromatography-mass spectrometry method, we found that there are significant differences in the composition of the volatile aroma and flavor compounds secreted by the mycelia cultivated in different media.

Background/aims: Dialysis membrane has been implicated in selenium (Se) deficiency in hemodialysis (HD). Intradialytic Se removal into dialysate through different membranes was investigated., Methods: We studied 19 patients on standard HD with low-flux polysulfone membrane (group A), 10 patients on standard HD with ethylene vinyl alcohol membrane (group B), 12 patients on hemodiafiltration (HDF; group C) and 16 healthy subjects (control group D). Se was measured in blood before and after dialysis session and in effluent dialysate every hour during session., Results: In all patients together, pre-dialysis serum Se levels were lower than those in control group, but, in a separate analysis, only in standard HD. In all patient groups, there was a net Se removal into dialysate but it was greater in HDF patients who, however, had similar pre-dialysis serum Se levels to those in healthy controls., Conclusion: An intradialytic Se loss was found with all 3 membrane types, but it is not the principal factor for Se depletion in HD., (© 2015 S. Karger AG, Basel.)

During the recent years, capillary electrophoresis (CE) has been fully established as a powerful tool in separation sciences as well as in element speciation. This road of success is based on the rapid analysis time, low sample requirements, high separation efficiency, and low operating costs of CE. Inductively coupled plasma mass spectrometry (ICP-MS) is known for superior detection and multielement capability. Consequently, the combination of both instruments is approved for analysis of complex sample types at low element concentrations which require high detection power. Also the diversity of potential applications brings CE-ICP-MS coupling into central focus of element speciation. The key to successful combination of ICP-MS as an (multi-)element selective detector for CE is the availability of a suitable and effective interface.Therefore, this chapter summarizes the most important and basic principles about coupling of capillary electrophoresis to ICP-MS. Specifically, the major requirements for interfacing are described and technical solutions are given. Such solutions include the closing of the electrical circuit from CE at the nebulization, the adoption of flow rates for efficient nebulization, the reduction of a suction flow through the capillary, caused by the nebulizer, and maintaining the high separation resolution from CE across the interface for ICP-MS detection. Additionally, detailed information is presented to determine and quantify the siphoning suction through the CE capillary by the nebulizer. Finally, two applications, namely, the manganese and selenium speciation in cerebrospinal fluid are shown as examples, providing the relevant operational parameter.

Selenium has unique fate and transport through a coal-fired power plant because of high vapor pressures of oxide (SeO2) in flue gas. This study was done at full-scale on a 900 MW coal-fired power plant with electrostatic precipitator (ESP) and wet flue gas desulfurization (FGD) scrubber. The first objective was to quantify the partitioning of selenium between gas and condensed phases at the scrubber inlet and outlet. The second objective was to determine the effect of scrubber operation conditions (pH, mass transfer, SO2 removal) on Se removal in both particulate and vapor phases. During part of the testing, hydrated lime (calcium hydroxide) was injected upstream of the scrubber. Gas-phase selenium and particulate-bound selenium were measured as a function of particle size at the inlet and outlet of the scrubber. The total (both phases) removal of Se across the scrubber averaged 61%, and was enhanced when hydrated lime sorbent was injected. There was evidence of gas-to-particle conversion of selenium across the scrubber, based on the dependence of selenium concentration on particle diameter downstream of the scrubber and on thermodynamic calculations.

A new method for selenium speciation in fermented bean curd wastewater and juice was described. This method involved sample extraction with 5-sulfosalicylic acid (SSA)-functionalized silica-coated magnetic nanoparticles (SMNPs), capillary electrophoresis (CE) separation, and online detection with a modified electrothermal atomic absorption spectrometry (ETAAS) system. The modified interface for ETAAS allowed for the introduction of CE effluent directly through the end of the graphite tube. Elimination of the upper injection hole of the graphite tube reduced the loss of the anlayte and enhanced the detection sensitivity. The SSA-SMNPs were synthesized and used to extract trace amounts of selenite [Se(IV)], selenite [Se(VI)], selenomethionine (SeMet), and selenocystine (SeCys2) from dilute samples. The concentration enrichment factors for Se(VI), Se(IV), SeMet, and SeCys2 were 21, 29, 18, and 12, respectively, using the SSA-SMNPs extraction. The limits of detection for Se(VI), Se(IV), SeMet, and SeCys2 were 0.18, 0.17, 0.54, 0.49ngmL(-1), respectively. The RSD values (n=6) of method for intraday were observed between 0.7% and 2.9%. The RSD values of method for interday were less than 3.5%. The linear range of Se(VI) and Se(IV) were in the range of 0.5-200ngmL(-1), and the linear ranges of SeMet and SeCys2 were 2-500 and 2-1000ngmL(-1), respectively. The detection limits of this method were improved by 10 times due to the enrichment by the SSA-SMNP extraction. The contents of Se(VI) and Se(IV) in fermented bean curd wastewater were measured as 3.83 and 2.62ngmL(-1), respectively. The contents of Se(VI), Se(IV), SeMet, and SeCys2 in fermented bean curd juice were determined as 6.39, 4.08, 2.77, and 4.00ngmL(-1), respectively. The recoveries were in the range of 99.14-104.5% and the RSDs (n=6) of recoveries between 0.82% and 3.5%., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Biogenic selenium, Se(0), has colloidal properties and thus poses solid-liquid separation problems, such as poor settling and membrane fouling. The separation of Se(0) from the bulk liquid was assessed by centrifugation, filtration, and coagulation-flocculation. Se(0) particles produced by an anaerobic granular sludge are normally distributed, ranging from 50 nm to 250 nm, with an average size of 166±29 nm and a polydispersity index of 0.18. Due to its nanosize range and protein coating-associated negative zeta potential (-15 mV to -23 mV) between pH 2 and 12, biogenic Se(0) exhibits colloidal properties, hampering its removal from suspension. Centrifugation at different centrifugal speeds achieved 22±3% (1500 rpm), 73±2% (3000 rpm) and 91±2% (4500 rpm) removal. Separation by filtration through 0.45 μm filters resulted in 87±1% Se(0) removal. Ferric chloride and aluminum sulfate were used as coagulants in coagulation-flocculation experiments. Aluminum sulfate achieved the highest turbidity removal (92±2%) at a dose of 10(-3) M, whereas ferric chloride achieved a maximum turbidity removal efficiency of only 43±4% at 2.7×10(-4) M. Charge repression plays a minor role in particle neutralization. The sediment volume resulting from Al2(SO3)4 treatment is three times larger than that produced by FeCl3., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Increasing evidences suggest that nanoscale zero-valent iron (nZVI) is an effective agent for treatment and removal of selenium from water. For example, 1.3 mM selenite was quickly removed from water within 3 min with 5 g/L nZVI. In this work, reaction mechanisms of selenite [Se(IV)] in a single core-shell structured nanoscale zero-valent iron (nZVI) particle were studied with the method of spherical aberration corrected scanning transmission electron microscopy (Cs-STEM) integrated with X-ray energy dispersive spectroscopy (XEDS). This method was utilized to visualize solid phase translocation and transformation of Se(IV) such as diffusion, reduction, deposition and the effect of surface defects in a single nanoparticle. Se(IV) was reduced to Se(-II) and Se(0), which then formed a 0.5 nm layer of selenium at the iron oxide-Fe(0) interface at a depth of 6 nm from the surface. The results provided near atomic-resolution proof on the intraparticle diffusion-reduction of Se(IV) induced by nZVI. The STEM mapping also discovered that defects on the surface layer accelerate the diffusion of selenium and increase the capacity of nZVI for selenium sequestration., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Colloidal elemental selenium (Se(0)) adversely affects membrane separation processes and aquatic ecosystems. As a solution to this problem, we investigated for the first time the removal potential of Se(0) by electrocoagulation process. Colloidal Se(0) was produced by a strain of Pseudomonas fluorescens and showed limited gravitational settling. Therefore, iron (Fe) and aluminum (Al) sacrificial electrodes were used in a batch reactor under galvanostatic conditions. The best Se(0) turbidity removal (97 %) was achieved using iron electrodes at 200 mA. Aluminum electrodes removed 96 % of colloidal Se(0) only at a higher current intensity (300 mA). At the best Se(0) removal efficiency, electrocoagulation using Fe electrode removed 93 % of the Se concentration, whereas with Al electrodes the Se removal efficiency reached only 54 %. Due to the less compact nature of the Al flocs, the Se-Al sediment was three times more voluminous than the Se-Fe sediment. The toxicity characteristic leaching procedure (TCLP) test showed that the Fe-Se sediment released Se below the regulatory level (1 mg L(-1)), whereas the Se concentration leached from the Al-Se sediment exceeded the limit by about 20 times. This might be related to the mineralogical nature of the sediments. Electron scanning micrographs showed Fe-Se sediments with a reticular structure, whereas the Al-Se sediments lacked an organized structure. Overall, the results obtained showed that the use of Fe electrodes as soluble anode in electrocoagulation constitutes a better option than Al electrodes for the electrochemical sedimentation of colloidal Se(0).

A novel process by using chemical leaching followed by bacterial reductive precipitation was proposed for selenium recovery from kiln powder as a byproduct of cement manufacturing. The kiln powder at a slurry concentration of 10 w/v% with 0.25 M Na2CO3 at 28°C produced wastewater containing about 30 mg-Se/L selenium. The wastewater was diluted four-fold and adjusted to pH 8.0 as preconditioning for bioreduction. A bacterial strain Pseudomonas stutzeri NT-I, capable of reducing selenate and selenite into insoluble elemental selenium, could recover about 90% selenium from the preconditioned wastewater containing selenium of 5 mg-Se/L when supplemented with lactate or glycerol. The selenium concentrations in the treated wastewater were low around the regulated effluent concentration of 0.1 mg-Se/L in Japan.

Objectives: The aim of this study was the optimization of selenium determination in plasma samples with electrothermal atomic absorption spectrometry using experimental design methodology., Design and Methods: 11 variables being able to influence selenium analysis in human blood plasma by electrothermal atomic absorption spectrometry (ETAAS) were evaluated with Plackett-Burman experimental design. These factors were selected from sample preparation, furnace program and chemical modification steps. Both absorbance and background signals were chosen as responses in the screening approach. Doehlert design was used for method optimization., Results: Results showed that only ashing temperature has a statistically significant effect on the selected responses. Optimization with Doehlert design allowed the development of a reliable method for selenium analysis with ETAAS. Samples were diluted 1/10 with 0.05% (v/v) TritonX-100+2.5% (v/v) HNO3 solution. Optimized ashing and atomization temperatures for nickel modifier were 1070°C and 2270°C, respectively. A detection limit of 2.1μgL(-1) Se was obtained. Accuracy of the method was checked by the analysis of selenium in Seronorm™ Trace element quality control serum level 1. The developed procedure was applied for the analysis of total selenium in fifteen plasma samples with standard addition method. Concentrations ranged between 24.4 and 64.6μgL(-1), with a mean of 42.6±4.9μgL(-1)., Conclusions: The use of experimental designs allowed the development of a cheap and accurate method for selenium analysis in plasma that could be applied routinely in clinical laboratories., (Copyright © 2014 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.)

The adsorption of selenium (Se) on soil is important because of the relevance of Se to environmental and health issues. The adsorption of Se(IV) and Se(VI) was evaluated on soil samples from São Paulo State, Brazil, as a function of varying pH, and the experimental data were fitted to the constant capacitance model. Adsorption experiments were conducted for 15 soil samples, after the addition of 20 µmol L(-1) of either Se(IV) or Se(VI), and the adjusted pH ranged between 2.5 and 10. Selenite adsorption was high for all soils, decreased with increasing pH, and was strongly correlated with Fe and Al oxide content. In contrast, Se(VI) adsorption was very low at pH values commonly found in agricultural soils, except for the highly weathered Rhodic Acrudox. The constant capacitance model fitted the Se(IV) and Se(VI) adsorption data well. Optimizations of mono- and bidentate complexation and surface protonation constants were used for the Se(IV) adsorption data. For Se(VI), optimizations for the 2 monodentate species were employed., (© 2014 SETAC.)

In this work, rapidly synergistic cloud point extraction (RS-CPE) and ultrasound-assisted cloud point extraction (UA-CPE) were firstly compared and coupled with spectrophotometer for selenium preconcentration and detection. The established RS-CPE pretreatment was simple, rapid and high effective. The extraction time was only 1min without heating process. Under the effect of ultrasound, UA-CPE accomplished extraction efficiently although the extraction procedure was relatively time-consuming. In this study, RS-CPE and UA-CPE were firstly applied for selenium preconcentration and coupled with conventional spectrophotometer. Their applications were expanded and the analytical performance of spectrophotometric determination for selenium was considerably improved. The influence factors relevant to RS-CPE and UA-CPE were studied in detail. Under the optimal conditions, the limits of detection (LODs) for selenium were respectively 0.2μgL(-1) of RS-CPE and 0.3μgL(-1) of UA-CPE with sensitivity enhancement factors (EFs) of 124 and 103. The developed methods were applied to the determination of trace selenium in real water samples with satisfactory analytical results., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Selenium (Se) species, Se-methyl-seleno-cysteine (MeSeCys), seleno-cystine (SeCys2), seleno-methionine (SeMet), selenite (SeO3(2-)) and selenate (SeO4(2-)), in the three main anatomical tissues of bay scallops (Argopecten irradians), the adductor muscle, the mantle and the visceral mass, were completely released by enzymatic hydrolysis and detected by high performance liquid chromatography (HPLC) in combination with inductively coupled plasma mass spectrometry (ICP-MS). For the thorough hydrolysis of the proteins to free the Se species, bay scallop tissues were pre-treated (pre-hydrolyzed) with papain in a 1molL(-1) sodium bicarbonate solution containing 5mmolL(-1) sodium thiosulfate at 30-40°C for 24h, then hydrolyzed by the combination of Flavourzyme(®) 500 L, carboxypeptidase Y and trypsin (3+1+1) at 45°C, at a constant pH of 8.00 for 6h. Under the optimized conditions, the quantification limits of MeSeCys, SeCys2, SeMet, SeO3(2-) and SeO4(2-) were 0.69, 0.48, 0.93 0.53 and 1.22μgL(-1), respectively (equivalent to 0.14, 0.097, 0.19, 0.11 and 0.24μgg(-1) for real samples). The working curves in the concentration ranges of 2 to 500μgL(-1) were linear with all the RSD (n=5) smaller than 15% and regression coefficients greater than 0.999. The recoveries of the species for spiked samples at 4μgg(-1) (equivalent to 20μgL(-1) in the final hydrolyzates) levels all exceeded 90%. The developed method was validated by the determination of SeMet in SELM-1, a Se enriched yeast certified reference material (CRM). Selenate was the only absent species, whereas the other four species did exist in bay scallops., (Copyright © 2013 Elsevier B.V. All rights reserved.)

We have developed an on-line sequential photocatalyst-assisted digestion and vaporization device (SPADVD), which operates through the nano-TiO2-catalyzed photo-oxidation and reduction of selenium (Se) species, for coupling between anion exchange chromatography (LC) and inductively coupled plasma mass spectrometry (ICP-MS) systems to provide a simple and sensitive hyphenated method for the speciation analysis of Se species without the need for conventional chemical digestion and vaporization techniques. Because our proposed on-line SPADVD allows both organic and inorganic Se species in the column effluent to be converted on-line into volatile Se products, which are then measured directly through ICP-MS, the complexity of the procedure and the probability of contamination arising from the use of additional chemicals are both low. Under the optimized conditions for SPADVD - using 1g of nano-TiO2 per liter, at pH 3, and illuminating for 80 s - we found that Se(IV), Se(VI), and selenomethionine (SeMet) were all converted quantitatively into volatile Se products. In addition, because the digestion and vaporization efficiencies of all the tested selenicals were improved when using our proposed on-line LC/SPADVD/ICP-MS system, the detection limits for Se(IV), Se(VI), and SeMet were all in the nanogram-per-liter range (based on 3σ). A series of validation experiments - analysis of neat and spiked extracted samples - indicated that our proposed methods could be applied satisfactorily to the speciation analysis of organic and inorganic Se species in the extracts of Se-enriched supplements., (Copyright © 2013. Published by Elsevier B.V.)

Selenium is an essential element for the normal cellular function of living organisms. However, selenium is toxic at concentrations of only three to five times higher than the essential concentration. The inorganic forms (mainly selenite and selenate) present in environmental water generally exhibit higher toxicity (up to 40 times) than organic forms. Therefore, the determination of low levels of different inorganic selenium species in water is an analytical challenge. Solid-phase extraction has been used as a separation and/or preconcentration technique prior to the determination of selenium species due to the need for accurate measurements for Se species in water at extremely low levels. The present paper provides a critical review of the published methods for inorganic selenium speciation in water samples using solid phase extraction as a preconcentration procedure. On the basis of more than 75 references, the different speciation strategies used for this task have been highlighted and classified. The solid-phase extraction sorbents and the performance and analytical characteristics of the developed methods for Se speciation are also discussed., (Copyright © 2013 Elsevier B.V. All rights reserved.)

A novel dispersive liquid-liquid microextraction-solidified floating organic drop (DLLME-SFOD) method combined with fiber optic-linear array detection spectrophotometry has been developed for the indirect determination of selenium. The method is based on the oxidation of the I(-) to iodine by inorganic Se(IV). The produced I2 reacts with the excess of I(-) ions in acidic media to give triiodide ions. The I3(-) is then extracted into 1-undecanol by DLLME-SFOD upon the formation of an ion pair with cetyltrimethylammonium cation. The extracted ion pair is determined by measuring its absorption at 360 nm. The absorbance signal is proportional to the selenium concentration in the aqueous phase. Under optimum conditions, the method provided an enrichment factor of 250 with a detection limit of 16.0 μg L(-1) and a linear dynamic range of 40.0-1000.0 μg L(-1). The relative standard deviation was found to be 2.1% (n=7) at 100.0 μg L(-1) concentration level. The method was successfully applied to th e determination of selenium in water samples and selenium plus tablet., (Copyright © 2013 Elsevier B.V. All rights reserved.)

In this work the possibility of determination of selenium in water samples was studied by on-line coupling of electrochemical pre-concentration flow through unit and GFAAS. The pre-concentration unit was created from a commercial electrochemical flow through analyser EcaFlow (Istran Ltd.) and a special two-electrode electrochemical flow through cell. The pre-concentration cell consisted of a working electrode made of gold-coated porous carbon and auxiliary electrode made of a Pt-wire. The pre-concentration unit was connected with electrothermal atomisers through 6-way valve with sampling loop. Using the proposed on-line coupling the limit of detection reached 0.01 μg L(-1) for a 10 mL sample. The total linear range was between 0.03 and 10 μg L(-1). From the number of ions tested only PO4(3-) ions reduced the signal by about 10% for 50-fold excess. Using this method it was possible to determine Se (IV) or the total inorganic selenium following reduction of Se (VI) by boiling the sample in HCl. The procedure was validated by analysing reference materials and a variety of water samples. A good agreement with the results of ICP-MS was achieved for all samples., (Copyright © 2013 Elsevier B.V. All rights reserved.)

A new method was developed for the determination of organic and inorganic selenium in selenium-enriched rice by graphite furnace atomic absorption spectrometry detection after cloud point extraction. Effective separation of organic and inorganic selenium in selenium-enriched rice was achieved by sequentially extracting with water and cyclohexane. Under the optimised conditions, the limit of detection (LOD) was 0.08 μg L(-1), the relative standard deviation (RSD) was 2.1% (c=10.0 μg L(-1), n=11), and the enrichment factor for selenium was 82. Recoveries of inorganic selenium in the selenium-enriched rice samples were between 90.3% and 106.0%. The proposed method was successfully applied for the determination of organic and inorganic selenium as well as total selenium in selenium-enriched rice., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Nowadays, hollow fiber membrane extraction techniques are widely used due to the high enrichment factors obtained with many different types of analytes and samples. In this paper, we propose a new analytical method that allows the simultaneous extraction of methylmercury, inorganic mercury and Se(4+) and determination by high performance liquid chromatography coupled to inductively coupled plasma mass spectrometry (HPLC-ICP-MS). The detection limits obtained are very low (110-230ng/L) with relative standard deviations below 15% for all the analytes and averaged recoveries in fortified samples in the range of 71-99%. The precision of the analytical method is very good which overcomes one of the most important shortcomings of membrane extraction techniques. Several variables were studied to get optimal extraction conditions for the analytes. This method has been validated with real world samples such as water (tap, river and estuarine) and human blood plasma., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Plant samples of Cardamine hupingshanesis (Brassicaceae), Ligulariafischeri (Ledeb.) turcz (Steraceae) and their underlying top sediments were collected from selenium (Se) mine drainage areas in Enshi, China. Concentrations of total Se were measured using Hydride Generation-Atomic Fluorescence Spectrometry (HG-AFS) and Se speciation were determined using liquid chromatography/UV irradiation-hydride generation-atomic fluorescence spectrometry (LC-UV-HG-AFS). The results showed that C. hupingshanesis could accumulate Se to 239±201 mg/kg DW in roots, 316±184 mg/kg DW in stems, and 380±323 mg/kg DW in leaves, which identifies it as Se secondary accumulator. Particularly, it could accumulate Se up to 1965±271 mg/kg DW in leaves, 1787±167 mg/kg DW in stem and 4414±3446 mg/kg DW in roots, living near Se mine tailing. Moreover, over 70% of the total Se accumulated in C. hupingshanesis were in the form of selenocystine (SeCys2), increasing with increased total Se concentration in plant, in contrast to selenomethionine (SeMet) in non-accumulators (eg. Arabidopsis) and secondary accumulators (eg. Brassica juncea), and selenomethylcysteine (SeMeCys) in hyperaccumulators (eg. Stanleya pinnata). There is no convincing explanation on SeCys2 accumulation in C. hupingshanesis based on current Se metabolism theory in higher plants, and further study will be needed.

Removal of the toxic selenium compounds selenite and selenate from waste water before discharge is becoming increasingly imperative in industrialized countries. Bacteria can reduce selenate to selenite, but also further to elemental selenium, selenide or organic selenium. In this paper, we aim to exclusively bio-reduce selenate to selenite in an open high-rate bioreactor. This conversion could be part of a two-stage process in which the selenite is subsequently reduced by chemical means under optimal conditions to produce a biomass-free selenium product. In the process, yield and reduction rate of biological selenate to selenite should be maximized, while formation of elemental selenium, selenide and organic selenium compounds should be avoided. Fed-batch experiments with a liquid volume of 0.25-0.75 L at different temperatures 20-30-40-50 °C, pH settings 6-7-8-9, initial biomass concentration of 1 or 5 g wet weight granular Eerbeek sludge and various lactic acid concentrations were performed to determine their effect on the biological conversion of selenate to selenite. Furthermore, the effect on selenite losses by further biological reduction or, if present, chemical reduction was investigated as well. Optimal selenate reduction to selenite was found at 30 °C and pH 6 or 7 or 8 with 25 mM selenate and 13.75 mM lactic acid in the influent, with a selenite yield of 79-95%. In all the other conditions, less selenate was reduced to selenite. Also a 5 times higher electron donor concentration resulted in less selenite production, with only 22% of the selenate converted to selenite. The high yield and the high biological reduction rate of at least 741 mg Se/g initial VSS/day detected in the 1 g initial biomass experiment implicate that biological selenate conversion to selenite is a feasible process., (Copyright © 2013 Elsevier Ltd. All rights reserved.)