Human serum albumin-bound selenium (Se-HSA) in serum and its correlation with other selenium species.

INTRODUCTION: Selenium (Se) is a trace element with different toxicological and nutritional properties according to its chemical forms. Among the wide range of selenium species, human serum albumin-bound selenium (Se-HSA) has still uncertain composition in terms of organic or inorganic selenium species. This study aimed at investigating the relation between Se-HSA levels with total selenium and the specific organic and inorganic selenium species. METHODS: We determined levels of total selenium and selenium species in serum of participants enrolled in two populations of the Emilia-Romagna region, in Northern Italy. Anion exchange chromatography coupled with inductively coupled plasma dynamic reaction cell mass spectrometry was used as quantification method. Correlations between Se-HSA and the other selenium compounds were analyzed using linear regression and restricted cubic spline regression models, adjusted for potential confounders. RESULTS: The first cohort comprised 50 participants (men/women: 26/24) with median (interquartile range, IQR) age 50 (55-62) years, while the second was composed of 104 participants (M/W: 50/54), median (IQR) age 48 (44-53) years. Median (IQR) levels of total selenium were 118.5 (109-136) µg/L and 116.5 (106-128) µg/L, respectively, while Se-HSA was 25.5 µg/L (16.2-51.5) and 1.1 (0.03-3.1) µg/L, respectively. In both populations, Se-HSA was positively associated with inorganic selenium species. Conversely, Se-HSA was inversely associated with organic selenium, especially with selenoprotein P-bound-Se (Se-SELENOP) and less strongly with selenomethionine-bound-Se (Se-Met), while the relation was null or even positive with other organic species. Evaluation of non-linear trends showed a substantially positive association with inorganic selenium, particularly selenite, until a concentration of 30 µg/L, above which a plateau was reached. The association with Se-SELENOP was inverse and strong until 100 µg/L, while it was almost null at higher levels. CONCLUSIONS: Our findings seem to indicate that Se-HSA incorporates more selenium when circulating levels of inorganic compounds are higher, thus supporting its mainly inorganic nature, particularly at high circulating levels of selenite.

The compound-independent calibration of five selenium species in rice using ion-pairing reversed phase chromatography coupled to inductively coupled plasma tandem mass spectrometry.

An enzyme-assisted extraction and an ion pairing reversed phase chromatography (IP-RPC) coupled to inductively coupled plasma tandem mass spectrometry (ICP-MS/MS) method were established for the simultaneous analysis of five selenium species in rice: selenious acid (SeIV), selenic acid (SeVI), selenocystine (SeCys2), methylselenocysteine (SeMeCys) and selenomethionine (SeMet). Optimal extraction efficiencies were obtained by using 15 mg protease XIV, water bath temperature of 45°C, pH of 6.5 and incubation of six hours. The total extracted Se species account for 92.5-109.3 % of the total Se in rice. The instrumental limits of detection for five selenium species ranged from 0.04 to 0.12 ng Se g-1. Spike recovery experiments performed on rice samples were in the range of 96.1-102.9 % for all analytes except for SeCys2 (66.1-77.1 %). A consistency of Se elemental response was observed among Se species analyzed in this study as the ratio of linear equation slope ranged from 1.020 to 1.036 (SeIV as reference) in rice matrix. The developed compound-independent calibration method was applied to detect Se species in eleven rice samples from China. Both selenium-enriched rice and regular rice were predominated with SeMet, accounting for ∼89.4 % of total selenium.

New Method for Simultaneous Arsenic and Selenium Speciation Analysis in Seafood and Onion Samples.

This paper presents a new method for the simultaneous speciation analysis of arsenic (As(III)-arsenite, As(V)-arsenate, DMA-dimethylarsinic acid, MMA-methylarsonic acid, and AsB-arsenobetaine) and selenium (Se(IV)-selenite, Se(VI)-selenate, Se-Methionine, and Se-Cystine), which was applied to a variety of seafood and onion samples. The determination of the forms of arsenic and selenium was undertaken using the High-Performance Liquid Chromatography Inductively Coupled Plasma Mass Spectrometry (HPLC-ICP-MS) analytical technique. The separation of both organic and inorganic forms of arsenic and selenium was performed using two analytical columns: an anion exchange column, Dionex IonPac AS22, containing an alkanol quaternary ammonium ion, and a double bed cation-anion exchange guard column, Dionex Ion Pac CG5A, containing, as a first layer, fully sulfonated latex for cation exchange and a fully aminated layer for anion exchange as the second layer. The ammonium nitrate, at pH = 9.0, was used as a mobile phase. The method presented here allowed us to separate the As and Se species within 10 min with a suitable resolution. The applicability was presented with different sample matrix types: seafood and onion.

Comparison of quantification of selenocyanate and thiocyanate in cultured mammalian cells between HPLC-fluorescence detector and HPLC-inductively coupled plasma mass spectrometer.

The simultaneous detection of cyanide (CN), thiocyanate (SCN), and selenocyanate (SeCN) by a HPLC-fluorescence detector (FLD) with the post-column König reaction was recently reported. SCN and SeCN are also detectable by HPLC-inductively coupled plasma mass spectrometry (HPLC-ICP-MS) because sulfur and selenium can be detected, respectively, without any pre- or post-treatment. ICP-MS has high sensitivity for selenium and sulfur detection and is robust to sample matrices. In this study, we compared HPLC-FLD with the post-column König reaction and HPLC-ICP-MS in terms of SCN and SeCN detection sensitivity and linearity. The limit of detection (LOD) for SCN indicated that HPLC-FLD with the post-column König reaction was 354 times more sensitive than HPLC-ICP-MS. Likewise, the LOD for SeCN indicated that HPLC-FLD was 51 times more sensitive than HPLC-ICP-MS. These results demonstrated that HPLC-FLD was a more suitable technique for SeCN and SCN detection than HPLC-ICP-MS. We previously reported that SeCN was generated in selenite-exposed mammalian cells to detoxify excess selenite. HPLC-FLD with the post-column König reaction enabled good separation and detection for quantifying SCN and SeCN in mammalian cell lines exposed to selenite. The intracellular SCN and SeCN concentrations determined by this technique suggested differences in the metabolic capacity for selenite to form SeCN among the cell lines. In addition, since the amount of intracellular SCN and SeCN were significantly decreased by pretreatment of myeloperoxidase (MPO) inhibitors, SCN and SeCN were resulted from the interaction of sulfur and selenium with endogenous CN, respectively, generated with MPO.

Investigation of Different Selenium Sources and Supplying Methods for Selenium Enrichment of Basil Vegetable (A Case Study under Calcareous and Non-calcareous Soil Systems).

BACKGROUND: Selenium (Se) is a crucial component of selenoaminoacids and selenoproteins. Therefore, Se-enriched agricultural products can reduce health complications induced by Se deficiency. OBJECTIVE: This research was carried out to investigate the effects of Se bio-enrichment on Basil grown in calcareous and non-calcareous soil systems and also to evaluate the changes in Se concentration in the soil after harvesting. METHODS: The experiment executed in two calcareous and one non-calcareous soil systems, and different Se application methods (control, soil application, seed inoculation, foliar application, and soil + foliar application) were administered. Selenobacteria, a plant growth-promoting rhizobacteria (PGPR), derived from the soil was used as a biofertilizer, compared to the other Se sources. RESULTS: The results showed that both soil types and the methods of Se application had significant effects (P ˂ 0.01) on root and shoot dry weights and concentrations of P, K, Zn, Fe, and Se in both of the root and shoot. Shoot dry weight of plants treated with foliar Se was maximum in the calcareous soil. Compared to the control treatment, foliar application of Se increased shoot Se content in both calcareous and non-calcareous soils by 242% and 204%, respectively. Furthermore, the increase in shoot Se concentration in calcareous soil induced by Se application increased the concentration of other nutrients in the shoot and root. Plant growth parameters and concentrations of nutrients were significantly increased by using selenobacter inoculum. CONCLUSION: The application of Se-containing compounds can improve vegetable quality. Considering the daily requirement of the human body for minerals and nutrients, enriching basil with Se can play an important role in community health. Moreover, some patents have reported the effectiveness of endophyte bacteria.

Selenium may suppress peripheral blood mononuclear cell apoptosis by modulating HSP70 and regulate levels of SIRT1 through reproductive hormone secretion and oxidant stress in women suffering fluorosis.

Excessive taking fluoride (F) causes severe damage to reproductive system through stimulation of apoptosis and oxidant stress. Selenium (Se) may promote anti-oxidant enzymes and invert cell apoptosis. The aim of this study was to investigate the effect of Se on peripheral blood mononuclear cell (PBMC) apoptosis and oxidant stress in women with fluorosis. Sixty women were divided into three groups according to serum and urine fluoride and hair Se as High F + high Se group, High F group and Control group. The activities of anti-oxidant enzymes, malondialdehyde (MDA) and Se were measured. The levels of sirtuin type 1 (SIRT1), estradiol (E2), follicle-stimulating hormone (FSH) and luteinizing hormone (LH) were measured by enzyme-linked immune sorbent assay (ELISA) kits. The expression of protein and apoptosis rate were detected by Western blot and Flow cytometry. The levels of E2, anti-oxidant enzymes in High F group were significantly lower than that in Control group, while the levels of SIRT1 and MDA were significantly higher. The levels of anti-oxidant enzymes and heat shock protein 70 (HSP70) were significantly increased in High Se + high F group while the expression of caspase-3 was significantly increased in high F group. The levels of LH and FSH in serum were significantly increased in High F group and High Se + high F group. Therefore, Se alleviates apoptosis induced by F through improving the expression of HSP70 and reduces oxidative stress by regulating levels of SIRT1 and anti-oxidant enzymes, and the secretion of certain reproductive hormones.

A review of bioselenol-specific fluorescent probes: Synthesis, properties, and imaging applications.

Bioselenols are important substances for the maintenance of physiological balance and offer anticancer properties; however, their causal mechanisms and effectiveness have not been assessed. One way to explore their physiological functions is the in vivo detection of bioselenols at the molecular level, and one of the most efficient ways to do so is to use fluorescent probes. Various types of bioselenol-specific fluorescent probes have been synthesized and optimized using chemical simulations and by improving biothiol fluorescent probes. Here, we review recent advances in bioselenol-specific fluorescent probes for selenocysteine (Sec), thioredoxin reductase (TrxR), and hydrogen selenide (H2Se). In particular, the molecular design principles of different types of bioselenols, their corresponding sensing mechanisms, and imaging applications are summarized.

Identification and determination of selenocysteine, selenosugar, and other selenometabolites in turkey liver.

Liver and other tissues accumulate selenium (Se) when animals are supplemented with high dietary Se as inorganic Se. To further study selenometabolites in Se-deficient, Se-adequate, and high-Se liver, turkey poults were fed 0, 0.4, and 5 µg Se g-1 diet as Na2SeO3 (Se(iv)) in a Se-deficient (0.005 µg Se g-1) diet for 28 days, and the effects of Se status determined using HPLC-ICP-MS and HPLC-ESI-MS/MS. No selenomethionine (SeMet) was detected in liver in turkeys fed either this true Se-deficient diet or supplemented with inorganic Se, showing that turkeys cannot synthesize SeMet de novo from inorganic Se. Selenocysteine (Sec) was also below the level of detection in Se-deficient liver, as expected in animals with negligible selenoprotein levels. Sec content in high Se liver only doubled as compared to Se-adequate liver, indicating that the 6-fold increase in liver Se was not due to increases in selenoproteins. What increased dramatically in high Se liver were low molecular weight (MW) selenometabolites: glutathione-, cysteine- and methyl-conjugates of the selenosugar, seleno-N-acetyl galactosamine (SeGalNac). Substantial Se in Se-adequate liver was present as selenosugars decorating general proteins via mixed-disulfide bonds. In high-Se liver, these "selenosugar-decorated" proteins comprised ∼50% of the Se in the water-soluble fraction, in addition to low MW selenometabolites. In summary, more Se is present as the selenosugar moiety in Se-adequate liver, mostly decorating general proteins, than is present as Sec in selenoproteins. With high Se supplementation, increased selenosugar formation occurs, further increasing selenosugar-decorated proteins, but also increasing selenosugar linked to low MW thiols.

Capabilities of asymmetrical flow field - Flow fractionation on-line coupled to different detectors for characterization of water-stabilized quantum dots bioconjugated to biomolecules.

The asymmetric flow field-flow fractionation (AF4) coupled on-line with elemental (inductively coupled plasma-mass spectrometry, ICP-MS) and molecular (fluorescence and UV) detection has been investigated as a powerful tool for the characterization of bioinorganic nano-conjugates. In this study, we described methods for the characterization of biotin-antibody complexes bioconjugated with streptavidin quantum dots (QDs-SA-b-Ab). Operating parameters of AF4 separation technique were optimized and two procedures are proposed using a channel thickness of 350 µm and 500 µm. The use of a 500 µm spacer allowed to achieve an efficient AF4 separation of the QDs-SA-b-Ab complexes from the excess of individual species used in the bioconjugation that was required for a proper characterization of the bioconjugates. Optimization of the AF4 allowed a separation resolution good enough to isolate the QDs-SA-b-Ab bioconjugates from the free excess of b-Ab and QD-SA. The efficiency of the bioconjugation process could be then calculated, obtaining a value of 86% for a 1 QDs-SA: 5 b-Ab bioconjugation ratio. In addition, sample recovery around 90% was achieved.

Development and application of a HPLC-ICP-MS method to determine selenium speciation in muscle of pigs treated with different selenium supplements.

Dietary selenium deficiency is recognized as a global problem. Pork is the most widely consumed meat throughout the world and an important source of selenium for humans. In this study, a reliable approach was developed for analyzing selenium and its speciation in the muscles of pigs after different selenium treatments. The selenium source deposition efficiency was ranked as: selenomethionine > methylselenocysteine > selenite, and the muscle selenium content had a dose effect with selenomethionine supplementation. In total, four species of selenium were detected in the muscles of pigs and the distributions of these selenium species were greatly affected by the dietary selenium supplementation forms and levels. Selenomethionine (>70% of total selenium) and selenocystine (>11%) were the major selenium species, followed by methylselenocysteine and selenourea. Therefore, selenium-enriched pork produced from selenomethionine is a good source for improving human dietary selenium intake.

Identification of the biliary selenium metabolite and the biological significance of selenium enterohepatic circulation.

Although selenium (Se) is mainly excreted in urine, it has been reported that an unknown Se metabolite is excreted in bile. When we administered selenomethionine (SeMet), selenocyanate or selenite to rats, a common biliary selenometabolite was detected 10 min after administration. The amount of the selenometabolite originating from SeMet was less than that originating from the two inorganic Se compounds, selenocyanate and selenite, suggesting that the transformation from the methylated organic selenocompound, i.e., SeMet, was less efficient than that from the inorganic Se compounds. The common biliary selenometabolite was concretely identified as selenodiglutathione (GSSeSG) by two types of mass spectrometry, i.e., LC-inductively coupled mass spectrometry (ICP-MS) and LC-ESI-Q/TOF. The bile-drained rats had lower urinary Se levels than the sham-operated rats. In addition, the Se amounts in urine plus bile of the bile-drained rats were comparable to the Se amount in the urine of the sham-operated rats. These results suggest that the biliary selenometabolite, GSSeSG, was reabsorbed in the gut and finally excreted in urine. Enterohepatic circulation occurs to maintain Se status in the body.

A novel cadmium-containing wastewater treatment method: Bio-immobilization by microalgae cell and their mechanism.

Heavy metal cadmium (Cd) has drawn tremendous comcern due to its rigorous environmental and health hazards. Herein, we have presented an efficient and economical strategy for the removal and recycling of hazardous Cd ions using microalgae cells as the bioreactors. Remarkably, the green bio-platform for the bioproduction of CdSe nanoparticles (NPs) was developed depending on their orderly regulated and sustainable cellular environment. The biofabricated CdSe NPs manifested favorable photoluminescence properties, and presented well monodispersed spherical morphology and certain crystallinity structure with mean size of smaller than 7 nm. Especially, the fluorescence "turn off" sensing system based on the CdSe NPs was established to detect Hg2+. The nanosensor enables the quantitative analyses of Hg2+ with a linear range of 0-2.0 µM and a detection limit of 0.021 µM. Furthermore, it was preliminarily speculated that the reducing biomolecules in the algae cells could be involved in the formation of CdSe NPs. This work not only provides new insights into the removal and recycling of hazardous Cd ions, but also brings a promising route for biosynthesis of CdSe NPs.

Triple-Labeling of Polymer-Coated Quantum Dots and Adsorbed Proteins for Tracing their Fate in Cell Cultures.

Colloidal CdSe/ZnS quantum dots were water solubilized by overcoating with an amphiphilic polymer. Human serum albumin (HSA) as a model protein was either adsorbed or chemically linked to the surface of the polymer-coated quantum dots. As the quantum dots are intrinsically fluorescent, and as the polymer coating and the HSA were fluorescent labeled, the final nanoparticle had three differently fluorescent components: the quantum dot core, the polymer shell, and the human serum albumin corona. Cells were incubated with these hybrid nanoparticles, and after removal of non-internalized nanoparticles, exocytosis of the three components of the nanoparticles was observed individually by flow cytometry and confocal microscopy. The data indicate that HSA is partly transported with the underlying polymer-coated quantum dots into cells. Upon desorption of proteins, those initially adsorbed to the quantum dots remain longer inside cells compared to free proteins. Part of the polymer shell is released from the quantum dots by enzymatic degradation, which is on a slower time scale than protein desorption. Data are quantitatively analyzed, and experimental pitfalls, such as the impact of cell proliferation and fluorescence quenching, are discussed.

Quantitative Assessment of Individual Populations Present in Nanoparticle-Antibody Conjugate Mixtures Using AF4-ICP-MS/MS.

A current remaining challenge in nanotechnology is the fast and reliable determination of the ratios between engineered nanoparticles and the species attached to their surface after chemical functionalization. The approach proposed herein based on the online coupling of asymmetric flow field-flow fractionation (AF4) with inductively coupled plasma-tandem mass spectrometry (ICP-MS/MS) allows for the first time the direct determination of such ratios in CdSe/ZnS core-shell quantum dot:rat monoclonal IgG2a antibody (QD:Ab) conjugate mixtures in a single run without any previous sample preparation (i.e., derivatization). AF4 provides full recovery and adequate resolution of the resulting bioconjugate from the excess of nanoparticles and proteins used in the different bioconjugation mixtures (1:1, 2:1, and 3:1 QD:Ab molar ratios were assessed). The point-by-point determination by ICP-MS/MS of the metal to sulfur ratios along the bioconjugate fractographic peak allowed disclosing the mixture of the different species in the bioconjugated sample, providing not only the limits of the range of QD:Ab ratios in the different bioconjugate species resulting after functionalization but also a good estimation of their individual relative abundance in the mixture. Interestingly, a wide variety of compositions were observed for the different bioconjugate mixtures studied (QD:Ab molar ratios ranging from 0.27 to 4.6). The resulting weighted QD:Ab ratio computed in this way for each bioconjugate peak matches well with both the global (average) QD:Ab ratio experimentally obtained by the simpler peak area ratio computation and the theoretical QD:Ab molar ratios assayed, which internally validates the procedure developed.

Copper-Driven Deselenization: A Strategy for Selective Conversion of Copper Ion to Nanozyme and Its Implication for Copper-Related Disorders.

Synthetic organic molecules, which can selectively convert excess intracellular copper (Cu) ions to nanozymes with an ability to protect cells from oxidative stress, are highly significant in developing therapeutic agents against Cu-related disorder like Wilson's disease. Here, we report 1,3-bis(2-hydroxyethyl)-1 H-benzoimidazole-2-selenone (1), which shows a remarkable ability to remove Cu ion from glutathione, a major cytosolic Cu-binding ligand, and thereafter converts it into copper selenide (CuSe) nanozyme that exhibits remarkable glutathione peroxidase-like activity, at cellular level of H2O2 concentration, with excellent cytoprotective effect against oxidative stress in hepatocyte. Cu-driven deselenization of 1, under physiologically relevant conditions, occurred in two steps. The activation of C═Se bond by metal ion is the crucial first step, followed by cleavage of the metal-activated C═Se bond, initiated by the OH group of N-(CH2)2OH substituent through neighboring group participation (deselenization step), resulted in the controlled synthesis of various types of Cu2-xSe nanocrystals (NCs) (nanodisks, nanocubes, and nanosheets) and tetragonal Cu3Se2 NCs, depending upon the oxidation state of the Cu ion used to activate the C═Se bond. Deselenization of 1 is highly metal-selective. Except Cu, other essential metal ions, including Mn2+, Fe2+, Co2+, Ni2+, or Zn2+, failed to produce metal selenide under identical reaction conditions. Moreover, no significant change in the expression level of Cu-metabolism-related genes, including metallothioneines MT1A, is observed in liver cells co-treated with Cu and 1, as opposed to the large increase in the concentrations of these genes observed in cells treated with Cu alone, suggesting the participation of 1 in Cu homeostasis in hepatocyte.

Sensitive and Selective Fluorescent Probe for Selenol in Living Cells Designed via a p Ka Shift Strategy.

Selenocysteine (Sec) is a primary kind of reactive selenium species in cells, and its vital roles in physiological processes have been featured. Thus, the development of highly sensitive and selective methods for the sensing of Sec is of great significance. This work reports a turn-on fluorescent probe for selenol based on the unique fluorescence OFF-ON switching between the Schiff base (SB) and its complementary protonated Schiff base (PSB) form of merocyanine dyes. The probe consists of a merocyanine Schiff base fluorophore and a 2,4-dinitrobenzenesulfonamide moiety that reacts especially with selenol. The fluorescence turn-on response of MC-Sec is realized via the selective removal of the strongly electron withdrawing 2,4-dinitrobenzenesulfonyl group by Sec, leading to a shift in the p Ka of the imine nitrogen of the probe from 6.40 to 9.04 and thus significantly increasing the population of the fluorescent PSB form of the dye at physiological pH. MC-Sec shows good selectivity and sensitivity for Sec and has been applied in the imaging of exogenous and endogenous selenol in living cells by confocal fluorescence microscopy. The proposed mechanism should be useful for developing future probes directed to other target molecules by employing this simple but effective p Ka shift strategy.

Hydrophilic interaction liquid chromatography in the speciation analysis of selenium.

The hydrophilic interaction liquid chromatography (HILIC) coupled to mass spectrometry was employed to study retention behavior of selected selenium compounds using two different HILIC stationary phases: silica and zwitterionic. Two organic solvents - acetonitrile and methanol - were compared as a component of mobile phase. Separation parameters such as a content of organic modifier, the eluent pH and inorganic buffer concentration were investigated. Based on all observations, methanol seems to be beneficial for the separation of studied compounds. The optimal HILIC separation method involved silica column and eluent composed of 85% MeOH and CH3COONH4 (8 mM, pH 7) was compared to RP method in terms of time of the single run, the separation efficiency and limit of detection.

Chip-based magnetic solid phase microextraction coupled with ICP-MS for the determination of Cd and Se in HepG2 cells incubated with CdSe quantum dots.

The quantification of trace Cd and Se in cells incubated with CdSe quantum dots (QDs) is critical to investigate the cytotoxicity of CdSe QDs. In this work, a miniaturized platform, namely chip-based magnetic solid phase microextraction (MSPME) packing with sulfhydryl group functionalized magnetic nanoparticles, was fabricated and combined with inductively coupled plasma mass spectrometry (ICP-MS) for the determination of trace Cd and Se in cells. Under the optimized conditions, the limits of detection (LOD) of the developed chip-based MSPME-ICP-MS system are 2.2 and 21ngL-1 for Cd and Se, respectively. The proposed method is applied successfully to the analysis of total and released small molecular fraction of Cd and Se in Human hepatocellular carcinoma cells (HepG2 cells) incubated with CdSe QDs, and the recoveries for the spiked samples are in the range of 86.0-109%. This method shows great promise to analyze cell samples and the obtained results are instructive to explore the cytotoxicity mechanism of CdSe QDs in cells.

Simultaneous Speciation of Selenoproteins and Selenometabolites in Plasma and Serum.

Selenium is an essential element incorporated to different proteins with important biological functions in connection to antioxidant activity, cancer-protective properties, neurodegenerative pathologies, and prevention of effects of diabetes, among others. In addition, selenoamino acids play a basic role in the global equilibrium of key selenium-biomolecules synthesis, including selenoprotein P, selenoalbumin, and glutathione peroxidase. Homeostasis of these selenium-containing biomolecules involves different organs in living organisms including human, and bloodstream is the connection fluid in this process. Therefore, it is very important to have an analytical methodology suitable for selenium proteins and metabolites speciation in serum and plasma samples. For this purpose, a simultaneous speciation method for Se-containing biomolecules in serum/plasma is described on the basis of in series three-dimensional chromatography: size exclusion, affinity, and anion exchange high performance liquid chromatography (3D/SE-AF-AEC-HPLC), using different columns of each type and hyphenation to inductively coupled plasma-(quadrupole) mass spectrometry (ICP-MS). The method allows the quantitative simultaneous analysis of selenoprotein P (SeP), extracellular glutathione peroxidase (eGPx), selenoalbumin (SeAlb), selenite, and selenate in serum (from human and mouse) using species-unspecific isotope dilution (SUID). In addition, a simplified two-dimensional approach (2D/SE-AF-HPLC-SUID-ICP-MS) is described when selenium metabolites are globally analyzed. The method provides detection limits in the range 0.2-1.3 ng of Se g-1 and avoids typical interferences in this matrix from chloride and bromide with a chromatographic runtime less than 35 min.

The Level of Toxic Elements in Edible Crops from Seleniferous Area (Punjab, India).

The primary objective of the present study was to assess the level of selenium and toxic trace elements in wheat, rice, maize, and mustard from seleniferous areas of Punjab, India. The content of selenium (Se) and toxic trace elements, including aluminum (Al), arsenic (As), cadmium (Cd), mercury (Hg), nickel (Ni), lead (Pb), and tin (Sn), in crop samples was assessed using inductively coupled plasma mass-spectrometry after microwave digestion of the samples. The obtained data demonstrate that cultivation of crops on seleniferous soils significantly increased Se level in wheat, mustard, rice, and maize by a factor of more than 590, 111, 85, and 64, respectively. The study also showed that Se exposure affected toxic metal content in crops. In particular, Se-rich wheat was characterized by a significant decrease in Al, As, Ni, Pb, and Sn levels. The level of As, Cd, Ni, Pb, and Sn was significantly decreased in Se-rich rice, whereas As content was increased. In turn, the decrease in Al, As, Cd, Ni, Pb, and Sn levels in Se-rich maize was associated with a significant elevation of Hg content. Finally, Se-rich mustard was characterized by a significant increase in Al, As, and Hg levels, while the content of Ni, Pb, and Sn was significantly lower than the control levels. These findings should be taken into account while developing the nutritional strategies for correction of Se status. At the same time, the exact mechanisms underlying the observed differences are to be estimated.