Analysis of selenium nanoparticles in human plasma by capillary electrophoresis hyphenated to inductively coupled plasma mass spectrometry

One-pot preparation of magnetic composite containing boronic acid groups and aminated multwalled carbon nanotubes for the speciation of Se(IV) and Se(VI) in water and milk samples by combination with chromatographic quantification

Speciation of Se(IV) and Se(VI) is essential due to their significant differences in reactivity, toxicity and bioavailability. Efficient extraction is the pivotal step in the quantification of inorganic selenium species. In this work, a new magnetic nano-composite (MNC) containing boronic acid group and aminated multwalled carbon nanotubes was facilely fabricated by means of one-pot hydrothermal strategy. The prepared MNC contained abundant functional groups and satisfactory magnetic saturation value. Combining with magnetic solid phase extraction (MSPE) format, the MNC displayed satisfactory capture performance towards the complex formed by the coordination of Se(IV) and o-phenylenediamine (OPA). Adsorption isotherm and adsorption kinetics were studied in detail to investigate the adsorption procedure of Se(IV)/OPA complex on MNC. Under the optimal preparation conditions of MNC and extraction parameters, the MNC/MSPE was connected with HPLC equipped with a diode array detector (DAD) to quantify trace Se(IV) and Se(VI) species in water and milk samples. Se(VI) was reduced to Se(IV) and then the total inorganic Se was quantified by the developed method. Subtraction method was used to measure the concentration of Se(VI). The achieved limits of detection were in the ranges of 0.0082-0.013 μg/L and 0.041-0.13 μg/kg for water and milk samples, respectively. Recoveries in actual samples spiked with different amounts of analytes varied from 81.0 % and 117 %, and the RSDs for repeatability varied from 1.0 % to 10 %. In comparison with existing studies based on MSPE, the established method presents some merits such as greenness in the preparation of magnetic adsorbent, rapid extraction procedure, low cost and satisfactory sensitivity in the speciation of inorganic Se species.

Speciation of Selenium in Selenium-Enriched Foods by High-Performance Liquid Chromatography-Inductively Coupled Plasma-Tandem Mass Spectrometry

Herein, a method was established for the speciation of six selenium species by high performance liquid chromatography-inductively coupled plasma-tandem mass spectrometry (HPLC-ICP-MS/MS). The factors affecting separation were carefully investigated, including ionic strength, pH, and methanol content. Six species of selenium could be completely separated within 20 min, under the mobile phase of 25 mM citric acid in pH = 4.0 containing 2% methanol. The detection limits of selenite (Se(IV)), selenate (Se(VI)), selenomethionine (SeMet), selenocystine (SeCys2), methylselenocysteine (MeSeCys), and selenoethionine (SeEt) were 0.04, 0.02, 0.05, 0.02, 0.03, and 0.15 ng mL−1, respectively. To verify the practicality of this method, the analysis of selenium-enriched foods such as selenium-enriched spring water, selenium-enriched salts, and selenium-enriched tea were conducted, and recovery of 93.7–105% was achieved with RSD < 5%, revealing the high practical utility of the proposed method.

Fabrication of functional group-rich monoliths for magnetic field-assisted in-tube solid phase microextraction of inorganic selenium species in water samples followed by online chromatographic determination

Efficient separation and enrichment is a crucial step in the analysis of Se(IV) and Se(VI). In the present study, for the first time, online monolith-based magnetic field-assisted in-tube solid phase microextraction (MFA/IT-SPME) was applied to capture inorganic selenium species in water samples. To this aim, porous monoliths mixed with magnetic nanoparticles were synthesized in a silica capillary and employed as a microextraction column (MEC) for MFA/IT-SPME. After that, a magnetic coil utilized to induce variable magnetic fields in adsorption and desorption steps was entwined around the MEC. Se(IV) was coordinated with o-phenylenediamine to form a coordination compound that was infused onto the MEC to be captured. Results evidenced that application of magnetic field during the extraction procedure assisted the capture of the Se(IV)-OPA complex, with an enhancement in the extraction efficiency from 83% to 97%. Under the optimized conditions, MFA/IT-SPME was online combined with HPLC equipped with a diode array detector (DAD) to perform quantification of Se(IV) and Se(VI) in environmental water samples. Total inorganic Se was quantified after pre-reduction of Se(VI) to Se(IV) prior to applying the established approach, and a subtraction method was adopted to calculate the Se(VI) and Se(IV) contents. The limit of detection for Se(IV) was as low as 0.012 μg L^-1. The reliability of the suggested method was investigated by assaying Se(IV) and Se(VI) species in real-life water samples with satisfactory recoveries (81.1%-116%) and repeatability (RSDs below 9%).

Polymer Nanocomposites of Selenium Biofabricated Using Fungi

Nanoparticle-reinforced polymer-based materials effectively combine the functional properties of polymers and unique characteristic features of NPs. Biopolymers have attained great attention, with perspective multifunctional and high-performance nanocomposites exhibiting a low environmental impact with unique properties, being abundantly available, renewable, and eco-friendly. Nanocomposites of biopolymers are termed green biocomposites. Different biocomposites are reported with numerous inorganic nanofillers, which include selenium. Selenium is a micronutrient that can potentially be used in the prevention and treatment of diseases and has been extensively studied for its biological activity. SeNPs have attracted increasing attention due to their high bioavailability, low toxicity, and novel therapeutic properties. One of the best routes to take advantage of SeNPs' properties is by mixing these NPs with polymers to obtain nanocomposites with functionalities associated with the NPs together with the main characteristics of the polymer matrix. These nanocomposite materials have markedly improved properties achieved at low SeNP concentrations. Composites based on polysaccharides, including fungal beta-glucans, are bioactive, biocompatible, biodegradable, and have exhibited an innovative potential. Mushrooms meet certain obvious requirements for the green entity applied to the SeNP manufacturing. Fungal-matrixed selenium nanoparticles are a new promising biocomposite material. This review aims to give a summary of what is known by now about the mycosynthesized selenium polymeric nanocomposites with the impact on fungal-assisted manufactured ones, the mechanisms of the involved processes at the chemical reaction level, and problems and challenges posed in this area.