Decomposition of six common selenium species found in animal tissues using microwave digestion with nitric acid and ICP-MS

Selenized lactic acid bacteria microencapsulated by spray drying: A promising strategy for beef cattle feed supplementation

This study aimed to assess the technical feasibility of incorporating selenized Lactobacillus spp. microencapsulated via spray drying into cattle feed. Gum Arabic and maltodextrin were used as encapsulating agents. The encapsulation process was carried out with a drying air flow rate of 1.75 m3 /min, inlet air temperature of 90°C, and outlet air temperature of 75°C. The viability of the encapsulated microorganisms and the technological characteristics of the obtained microparticles were evaluated. Microorganisms were incorporated into beef cattle feed to supplement their diet with up to 0.3 mg of Se per kilogram of feed. The encapsulated particles, consisting of a 50/50 ratio of gum Arabic/maltodextrin at a 1:20 proportion of selenized biomass to encapsulant mixture, exhibited superior technical viability for application in beef cattle feed. Supplemented feeds displayed suitable moisture, water activity, and hygroscopicity values, ensuring the preservation of viable microorganisms for up to 5 months of storage, with an approximate count of 4.5 log CFU/g. Therefore, supplementing beef cattle feed with selenized and microencapsulated lactic acid bacteria represents a viable technological alternative, contributing to increased animal protein productivity through proper nutrition.

Analysis of Selenium in Fish Tissue: An Interlaboratory Study on Weight Constraints

Environmental monitoring programs that target fish tissues for selenium (Se) analysis present unique sampling and analytical challenges. Selenium monitoring programs ideally focus on egg/ovary sampling but frequently sample multiple tissues with varying lipid content, often target small-bodied fish species because of their small home ranges, and require reporting in units of dry weight. In addition, there is a growing impetus for nonlethal tissue sampling in fish monitoring. As a result, Se monitoring programs often generate low-weight tissue samples of varying lipid content, which challenges analytical laboratories to quantify tissue Se concentrations accurately, precisely, and at desired detection limits. The objective of the present study was to stress-test some conventional analytical techniques used by commercial laboratories in terms of their ability to maintain data quality objectives (DQOs) in the face of sample weight constraints. Four laboratories analyzed blind a suite of identical samples, and data were compared against a priori DQOs for accuracy, precision, and sensitivity. Data quality tended to decrease with decreasing sample weight, particularly when samples were less than the minimum weights requested by the participating laboratories; however, effects of sample weight on data quality were not consistent among laboratories or tissue types. The present study has implications for accurately describing regulatory compliance in Se monitoring programs, highlighting some important considerations for achieving high data quality from low-weight samples. Environ Toxicol Chem 2023;42:2119-2129. © 2023 SETAC.

Trimethylselenonium ion determination in human urine by high-performance liquid chromatography-hydride generation-atomic fluorescence spectrometry optimization of the hydride generation step

This work describes the intricacies of the determination of the trimethylselenonium ion (TMSe) in human urine via high-performance liquid chromatography-hydride generation-atomic fluorescence spectrometry (HPLC-HG-AFS). By definition, this technique requires that the separated TMSe can be online converted into a volatile compound. Literature data for the determination of TMSe via the hydride generation technique are contradictory; i.e., some authors claim that direct formation of volatile compounds is possible under reduction with NaBH₄, whereas others reported that a digestion step is mandatory prior to conversion. We studied and optimized the conditions for online conversion by varying the mobile phase composition (pyridine, phosphate, and acetate), testing different reaction coils, and optimizing the hydride generation conditions, although technically no hydride (H₂Se) is formed but a dimethylselenide (DMSe). The optimized conditions were used for the analysis of 64 urine samples of 16 (unexposed) volunteers and the determination of low amounts of TMSe (LOD = 0.2 ng mL^-1). Total (specific gravity-corrected) selenium concentrations in the urine samples ranged from 7.9 ± 0.7 to 29.7 ± 5.0 ng mL^-1 for individual volunteers. Four volunteers were characterized as TMSe producers (hINMT genotype GA) and 12 were non-producers (hINMT genotype GG). Urine of TMSe producers contained 2.5 ± 1.7 ng mL^-1 of TMSe, compared to 0.2 ± 0.2 ng mL^-1 for non-producers.

The leaching potential of sewage sludge and municipal waste incineration ashes in terms of landfill safety and potential reuse

Incinerations residues from different types of materials (sewage sludge incineration ash and municipal waste incineration ashes) can either be by-products used in industry, or can pose a serious environmental problem related to their composition and the presence of potentially hazardous elements. State regulations and standards indicate whether material is inert, non-hazardous or hazardous. These standards, however, do not provide a complete overview on the leaching behavior of potentially hazardous elements in the environment. This study presents the result of batch experiment performed in accordance with the PN-EN 12457-2 (2006) and PN-EN 12457-4 (2006) standards. The results indicated that the leachability of elements is strongly dependent on the mineral composition of the waste product (the concentration and composition of soluble phase), the chemical composition (the mobility of hazardous elements and their affinity to soluble minerals), and the pH. To ensure environmental safety a thorough characterization of the waste is required followed by qualitative assignment to a particular waste type based on available guidance. Furthermore, to avoid leaching of potentially harmful elements into soils or surface water, it is also paramount to perform environmental impact assessment of wastes used as by-product in industry e.g., as building or road construction materials (aggregate) and fertilizers.

Fibrous g-C3N4@Tio2 Nanocomposites-Based Dispersive Micro-Solid Phase Extraction for Chromium Speciation in Cow Milk by ICP-MS after Digestion Treatment with Artificial Gastric Juice

BACKGROUND

Chromium is an interesting element because its toxicity depends on its speciation. Thus, knowledge of Cr speciation in cow milk is essential to human health.

OBJECTIVE

This study aims to achieve real bioaccessible species in cow milk, including Cr(III), Cr(VI), residual, digestible, and total Cr.

METHODS

Samples were treated with artificial gastric juice, followed by dispersive micro-solid phase extraction (DMSPE) combined with ICP-MS for Cr speciation. Fibrous g-C3N4@TiO2 nanocomposites (FGCTNCs) were used as a novel adsorbent for DMSPE.

RESULTS

The method detection limits were 110 pg/g (Cr(III)) and 260 pg/g (Cr(VI)) for milk powder (0.1 g), and 5.1 pg/g (Cr(III)) and 13 pg/g (Cr(VI)) for liquid cow milk (2 mL). The relative standard deviations (RSDs), obtained by analyzing the standard solutions containing 1.0 ng/mL of the analytes in sequence for nine times, were 4.3% and 5.1% for Cr(III) and Cr(VI), respectively. Linearity was observed over the range of 4 magnitude orders with correlation coefficients better than 0.9961. The enrichment factor of 100 was obtained. The majority of Cr in the samples was transferred into digestion solution. The content of Cr(III) is much higher than that of Cr(VI) in the digestion solution.

CONCLUSIONS

This method has the advantages of reduced solvent consumption, less adsorbent dosage, and high extraction efficiency. It may become a valuable strategy for elemental species in food samples.

HIGHLIGHTS

The samples were treated with artificial gastric juice to avoid the inter-conversion of species. FGCTNCs exhibit the merits of N-rich functional groups and selective adsorption for the analytes.

The application of microwave digestion in decomposing some refractory ore samples with solid fusion agent

It is known that most of the refractory ore are the basis of national economy and widely applied in various fields, however, the complexity of the chemical composition and the diversity of the crystallinity in the mineral phases make the sample pre-treatment of refractory ore still remains a challenge. In this work, the complete decomposition of the refractory ore sample can be achieved just by exposing the solid fusion agent and the refractory ore sample in the microwave irradiation environment for a few minutes, and induced by a drop of water. A digestion time of 15 min for 3.0 g solid fusion agent mixture of sodium peroxide/sodium carbonate (Na₂O₂/Na₂CO₃) in a corundum crucible via microwave heating is sufficient to decompose 0.1 g refractory ore sample. An excellent microwave digestion solid agent should meet the following conditions, a good decomposition ability, an outstanding ability of absorbing microwave energy and converting it into heat quickly, a higher melting point than the decomposing temperature of the ore sample. In the research, the induction effect of water plays an important role for the microwave digestion. The energy which is released by the reaction of water and the solid fusion agent (Na₂O₂) is the key to decompose refractory ore samples with solid fusion agent, which replenished the total energy required for the microwave digestion and made the microwave digestion completed successfully. This microwave digestion technique has good reproducibility and precision, RSD % for Mo, Fe, Ti, Cr and W in the refractory ore samples were all better than 6, except RSD % for Be of about 8 because of the influence of matrix-effect. Meanwhile, the analysis results of the elements in the refractory ore samples provided by the microwave digestion technique were all in good agreement with the analysis results provided by the traditional fusion method except for Cr in the mixture ore samples. In the study, the non-linear dependence of the electromagnetic and thermal properties of the solid fusion agent on temperature under microwave irradiation and the selective heating of microwave are fully applied in this simple microwave technique. Comparing to the traditional fusion decomposition method, this microwave digestion technique is a simple, economical, fast and energy-saving sample pre-treatment technique.