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[Display omitted] • Garlic Se absorption and transportation were largely affected by Se speciation. • Organic Se was superior to inorganic Se in enriching Se and antagonizing Cd. • Bulb Se content treated with organic Se was about twice (or more) than inorganic Se. • Organic Se was significantly more effective in reducing Cd content than inorganic Se. • Se was mainly enriched in bulb, Cd was enriched in root under organic Se application. Currently, planting selenium-rich crops using inorganic selenium such as selenate and selenite is used to address human selenium deficiency problems. In this paper, besides the above two traditional inorganic selenium speciation, we chose a new organic selenium speciation of potassium selenocyanoacetate to investigate the different effects of selenium speciation on selenium absorption, selenium transformation and cadmium antagonism via foliar application. Planting experiments showed that the selenium content of garlic bulbs treated with organic selenium was 1.8–3.9 times higher than that of inorganic selenium. Additionally, the absorption and transformation efficiency of organic selenium in garlic was also the highest, reaching over 95 %. Importantly, it was noteworthy that the cadmium content in bulbs treated with organic selenium was significantly lower than the Chinese food safety standard (0.2 mg/kg). Hence, this study provides an efficient organic selenium speciation which is beneficial to meet human selenium requirements and ensure safe utilization of cadmium-contaminated soils. [ABSTRACT FROM AUTHOR]

[Display omitted] • A 2,3-diaminonaphthalene post-synthetic modified magnetic MOF was fabricated. • The material was applied to the selective extraction of inorganic selenium. • The material exhibited selectivity toward Se(IV) at a pH of 2.5. • LOD and linear range were 8.0 ng/L and 25–8000 ng/L, respectively. • The analytical applicability was confirmed in various food, and water samples. In this work, a 2,3-diaminonaphthalene post-synthetic modified magnetic metal–organic framework was fabricated for fast and selective determination of inorganic selenium in real food and water samples. The results exhibited that selenium (IV) is adsorbed by the nano-material at a pH of 2.5, and in this way, selenium (IV) can be quantified selectively. After identifying the nanosorbent with FT-IR, CHNS, XRD, SEM, TEM, VSM, and BET surface analysis, parameters affecting the retention and desorption were optimized. Under optimal conditions, the detection limit of 8 ng/L was achieved for selenium (IV), and the method's precisions were less than 12.5 % intra-day RSD% and < 14.4 % for inter-day RSD%. The highest adsorption capacity was obtained as 264 mg/g. Finally, the desired adsorbent was used to extract and determine selenium species in water samples and total selenium in food samples. One of the most important advantages of the present method is its speed, ease, time-saving, and high accuracy. [ABSTRACT FROM AUTHOR]

• Lactic acid bacteria convert sodium selenite into organic selenocysteine and elemental Nano-selenium. • Lactic acid bacteria were selected on their ability to grow in a sodium selenite medium and to convert selenite to organic and Nano-Se. • The ability of lactic acid bacteria to act as silage inoculants was not compromised by the addition of sodium selenite. • Lactic acid bacteria inoculants can convert sodium selenite in silo to supplement livestock with organic and predominately Nano-Se. Selenium (Se) is a non-metallic trace element essential for normal cellular function, which has been linked with reduced risk of cancer, cardiovascular disease, cognitive decline and thyroid disease in humans. Se deficiency in livestock is associated with white muscle disease, retained placenta, ill-thrift and mastitis. Where Se status or bioavailability from the soil for plants is poor, livestock rely on supplemental Se in their diets predominantly as either sodium selenite (inorganic form) or selenised-yeast (organic form). As lactic acid bacteria (LAB) have been shown to incorporate Se as either organic or elemental (Nano-Se) there may be potential to use silage inoculant bacteria to improve the Se status of feed to provide the Se requirements of livestock. We screened twenty-seven LAB in MRS broth in the presence of sodium selenite for growth and uptake of Se as organic (selenocysteine and selenomethionine), inorganic (selenite and selenate) or/and Nano-Se, with the aim to identify potential candidates for a mini-silo study. Sodium selenite addition into the growth medium of LAB reduced growth rates but also resulted in the conversion of the inorganic sodium selenite into predominately Nano-Se and small quantities of organic-Se. Based on a rank analysis of growth and ability to take up (total Se content) and convert inorganic Se (Nano and organic Se content), three LAB were selected for further investigation as silage inoculants: L. brevis DSMZ (A), L. plantarum LF1 (B), and L. plantarum SSL MC15 (C). Each LAB was used as an inoculant within a grass mini-silo trial, either cultured in the presence of sodium selenite before inoculation or sodium selenite added to the inoculum at inoculation versus controls with no Se. The addition of sodium selenite either into the growth media of LAB or applied at inoculation of grass silage did not interfere with the ability of the LAB to act as a silage inoculant with no difference in silage fermentation characteristic between LAB with no Se added. The addition of sodium selenite either to the LAB growth medium or at inoculation resulted in the conversion of sodium selenite into Nano-Se and organic-Se (Nano-Se, ca. 103 higher than organic), as previously shown in the screening trial. There was no difference between the three LAB for incorporation of Se or in silage quality, indicating the potential to develop silage inoculants to increase the bioavailable form of Se (elemental and organic) to livestock through conversion of inorganic forms during ensiling. [ABSTRACT FROM AUTHOR]

This study aimed to assess the interaction between vitamin B 6 and selenium (Se) for the flow of Se towards the Se-dependent glutathione peroxidase (GPX) system in response to oxidative stress naturally induced by oestrus in a pubertal pig model. At first oestrus, forty-five gilts were randomly assigned to the experimental diets ( n = 9/group): basal diet (CONT); CONT + 0.3 mg/kg of Na-selenite (MSeB 6 0); MSeB 6 0 + 10 mg/kg of HCl-B 6 (MSeB 6 10); CONT + 0.3 mg/kg of Se-enriched yeast (OSeB 6 0); and OSeB 6 0 + 10 mg/kg of HCl-B 6 (OSeB 6 10). Blood samples were collected at each oestrus (long-term profiles), and daily from day −4 to +3 (slaughter) of the fourth oestrus (peri-oestrus profiles) after which liver, kidneys, and ovaries were collected. For long-term profiles, CONT had lower blood Se than Se-supplemented gilts ( p < 0.01) and OSe was higher than MSe ( p < 0.01). Lower erythrocyte pyridoxal-5-phosphate was found in B 6 0 than B 6 10 ( p < 0.01). No treatment effect was observed on GPX activity. For peri-oestrus profiles, treatment effects were similar to long-term profiles. Treatment effects on liver Se were similar to those for long-term blood Se profiles and OSe had higher renal Se concentrations than MSe gilts ( p < 0.01). Gene expressions of GPX1 , GPX3 , GPX4 , and selenocysteine lyase in liver and kidney were greatest in OSeB 6 10 gilts ( p < 0.05). These results suggest that dietary B 6 modulate the metabolic pathway of OSe towards the GPX system during the peri-oestrus period in pubertal pigs. [ABSTRACT FROM AUTHOR]

Highlights: [•] The use of solid phase extraction for speciation of inorganic Se is described. [•] Different SPE strategies and sorbents used for inorganic selenium speciation are discussed. [•] Analytical methods for speciation of inorganic Se in water samples are reviewed. [Copyright &y& Elsevier]

Abstract: A useful preconcentration and determination method was proposed for trace selenium in food samples. The procedure is based on complex formation of Pyronine B with Se(IV) ions in the presence of sodium dodecyl sulphate (SDS) and Ponpe 7.5. The variables affecting complex formation, extraction and phase separation were studied and optimised. Under the experimental conditions used, the calibration graph was linear in the range of 20–1700μgL−1 for Se(IV) ions. The limit of detection was 3.81μgL−1 of Se(IV) and the relative standard deviation for 5 replicate determinations at 250μgL−1concentration level was 2.45%. Recovery values were obtained between 97.8% and 102.8% for spiked samples. The method was successfully applied to the determination of total selenium in some food samples and alcoholic and nonalcoholic beverages. Its validity was checked by the analysis of four certified reference materials. The results obtained by the proposed method were quantitatively in good agreement with the certified values. [Copyright &y& Elsevier]

Abstract: Herein, ultrasound-assisted emulsification microextraction (USAEME) and dispersive liquid–liquid microextraction (DLLME) methods based on applying low-density organic solvents have been critically compared for the speciation of inorganic selenium, Se(IV) (selenite) and Se(VI) (selenate) in environmental water samples by gas chromatography-flame ionization detection (GC-FID). At pH 2 and T =75°C for 7min, only Se(IV) was able to form the piazselenol complex with 4-nitro-o-phenylenediamine. Piazselenol was extracted using an extraction solvent and was injected into a GC-FID instrument for the determination of Se(IV). Conveniently, Se(VI) remained in the aqueous phase. Total inorganic selenium was determined after the reduction of Se(VI) to Se(IV) and prior to the above procedures. The Se(VI) concentration was calculated as the difference between the measured total inorganic selenium and Se(IV) content. The effect of various experimental parameters on the efficiencies of the two methods and their optimum values were studied with the aid of response surface methodology and experimental design. Under the optimal conditions, the limit of detections (LODs) for Se(IV) obtained by USAEME-GC-FID and DLLME-GC-FID were 0.05 and 0.11ngmL−1, respectively. The relative standard deviations (RSDs, n =6) for the measurement 10ngmL−1 of Se(IV) were 5.32% and 4.57% with the enrichment factors of 2491 and 1129 for USAEME-GC-FID and DLLME-GC-FID, respectively. Both methods were successfully applied to the analysis of inorganic selenium in different environmental water samples and certified reference material (NIST SRM 1643e). [Copyright &y& Elsevier]

Speciation of selenium (Se) is typically carried out using a sophisticated technique such as ICP-MS after preconcentration using an adsorbent; however, the separation and preconcentration of inorganic Se has not been realized in the solutions containing high concentrations of SO 4 2–. A dithiocarbamate-modified cellulose (DMC) was used in this study for the selective extraction and preconcentration of inorganic Se in wastewater, with a portable liquid electrode plasma-optical emission spectrometry (LEP-OES) being employed for quantification. DMC was found to selectively and quantitatively adsorb selenite (SeIV) over a wide range of pH (1.0–8.0); however, less than 3.0% of selenate (SeVI) was adsorbed in a pH range of 3.0–11. Quantitative extraction of SeIV was achieved even in the presence of 3.5 mol L–1 SO 4 2–. The maximum sample volume from which 10 mg of DMC could quantitatively extract SeIV was found to be 500 mL. KOH (0.60 mL, 1.5 mol L–1) was found to quantitatively desorb SeIV retained on the adsorbent and yielded an enrichment factor of 833. The recovery of Se species from synthetic flue-gas desulfurization wastewater containing SeIV and SeVI at concentrations of 5.0 µmol L–1 was 96.2 ± 1.8% and 105.8 ± 1.8%, respectively. [Display omitted] • The adsorbent exhibited outstanding selectivity and capacity with respect to SeIV. • The selectivity of the adsorbent was higher than that of commercial resins. • A portable low-cost analyzer based on LEP-OES was used to quantify selenium. • The developed analytical method was applied to flue-gas desulfurization wastewater. • An accessible and simple method for the speciation of Se was established. [ABSTRACT FROM AUTHOR]

Abstract: The experiment was conducted to compare the effect of different selenium sources on the expression of glutathione peroxidase 1 (GPx1) and iodothyronine deiodinase 1 (Dio1) mRNA in mice by quantitative real-time PCR. A total of 60 male Kunming mice at average body weight of 20g were allotted to three groups in a randomized complete block design, namely two treatments and one control. Mice in Group 1 were fed a basal diet as control, while mice in Groups 2 and 3 were fed the basal diet supplemented with 0.1mg/kg selenium as sodium selenite or selenized yeast, respectively. Whole feeding experiment lasted for 30d. At the end of the feeding trial, liver mRNA levels of GPx1 and Dio1 were determined by quantitative real-time PCR, as well as growth performance, body composition, blood and GPx activity were determined. The results showed that no significant differences in overall growth performance and body composition, including body weight, body length, heart weight, kidney weight and liver weight, were found between the experimental groups (P>0.05). Blood GPx activity increased in all of the selenium supplemented groups compared with control group (P<0.01). However, blood GPx activity in selenized yeast group was higher than that in sodium selenite group (P<0.05). Liver mRNA levels of GPx1 and Dio1 also increased in the two selenium supplemented groups compared with the control group (P<0.05), while there was no significant difference between the sodium selenite and selenized yeast groups (P>0.05). In conclusion, selenium increased the mRNA expression of GPx1 and Dio1 genes in murine liver, and there was no significant difference between the organic or inorganic form of selenium used. [Copyright &y& Elsevier]

Abstract: A flow injection system with anion exchange resin minicolumns was coupled with dynamic reaction cell (DRC™) ICP-MS for the determination and speciation of selenite and selenate at sub μgL−1 levels. The charged selenate and uncharged selenite were separated on the first resin column in which only selenate was retained. The unretained selenite was then deprotonated with alkaline solution, and the resulting anionic selenite species was collected on the second column serially connected downstream. By setting a sample loop, total selenium can be determined together with selenite and selenate. The selenium species was eluted by nitric acid and carried to DRC™ ICP-MS for their detection. Using ammonia as reaction gas, the detection of 78Se was improved. The enrichment factor was 20 for 10mL of sample. The standard deviations (n =5) of peak heights were 4.9%, 4.1%, and 7.0% for a 5.0×10−2 μgL−1 selenite and selenate, and total Se, respectively. The calibration graphs were linear from 2.0×10−2 to 1.0μgL−1 selenite and selenate. And, the linearity for total selenium was good in the range of 10.0×10−2 to 1.0μgL−1. The proposed method has been demonstrated for the application to natural and bottled drinking water samples. [Copyright &y& Elsevier]

This paper describes the combined use of a new preconcentration method using the Amberlite IRA-743 resin and high-performance liquid chromatography coupled to inductively coupled plasma mass spectrometry to determine simultaneously inorganic and organic selenium species in aquatic systems. The developed enrichment procedure, whose accuracy has been checked by recovery tests, is suitable for selenium speciation at environmental levels of 10 ng (Se) l−1. The method has been applied to mineral and freshwater samples. [Copyright &y& Elsevier]