Occurrence, toxicity, and speciation analysis of arsenic in edible mushrooms

Anodic stripping voltammetry of arsenic determination with edible mushroom-nafion-modified glassy carbon electrode

An edible Mushroom-Nafion modified glassy carbon electrode (M2N5-GCE) was prepared using a homogeneous mixture varying the concentrations of these, in addition to the origin of the mushroom (Shiitake, Lentinula edodes, M1 and Abrantes, Agariscus bisporus, M2) and applied to the As(III) determination by anodic stripping voltammetry. After choosing the optimal conditions in the preparation of the electrode, the second stage was to study the effects of various parameters such as supporting electrolyte, pH, accumulation potential, and time (Eacc, tacc). The optimum experimental conditions chosen were Britton Robinson buffer 0.01 mol L-1 pH:4.6; Eacc: -1.0 and tacc: 60 s obtaining a signal of oxidation of As(0) to As(III) about 0.08 V. Peak current was proportional to arsenic concentration over the 19.6-117.6 μg L-1 range, with a 3σ detection limit of 13.4 μg L-1. The method was validated using As(III) spiked tap water from the laboratory with satisfactory results (RE:3.0 %). Finally, the method was applied to the determination of As(III) in water samples from the Loa River (Northern Chile) in the presence of As(V) in a concentration >20 times higher (RE: 2.3 %).

Synergistic photocatalytic oxidation and adsorption boost arsenic removal by in-situ carbon-doped TiO2 and nitrogen deficiency C3N4 heterojunction

The efficient removal of arsenic from wastewater is still a challenge. In this paper, a heterojunction consisting of in-situ carbon-doped TiO2 and nitrogen deficiency g-C3N4 (C/TiO2@ND-C3N4) has been constructed, which can completely oxidize As(III) (10,000 μg/L, 40 mL) to As(V) within 12 min under visible light and simultaneously adsorb total As (95.0%) with the pseudo-secondary kinetic equation, superior than in-situ carbon-doped TiO2 (75.0%) and nitrogen deficiency g-C3N4 (50.5%). The good photocatalytic oxidation and adsorption performances of C/TiO2@ND-C3N4 on As(III) removal can be attributed to the successful synthesis of heterojunction. On one hand, the building of C-O-Ti interfacial chemical bonds enable rapid electron transfer and improve the efficiency of photocatalytic oxidation. On the other hand, the decreased As(V) adsorption energy resulted from the synthesized heterojunction boost the adsorption capability of As(V), which was completed by the generation of O-As bonds with oxygen-containing functional groups on the surface of TiO2 and hydrogen bonds with high content pyrrole nitrogen derived from ND-C3N4, respectively. The results manifest that the preparation of bifunctional materials with both photocatalytic oxidation and adsorption properties provides a new strategy to achieve the removal of As.

LC/ICP-MS AND COMPLEMENTARY TECHNIQUES IN BESPOKE AND NONTARGETED SPECIATION ANALYSIS OF ELEMENTS IN FOOD SAMPLES

Chemical elements speciation analysis of food samples has been among the most important scientific topics over the last decades. Food samples are comprised of high variety of chemical compounds, from which many can interact with metals and metalloids, forming complex elemental species with various influence on the human body. It is particularly important not only to determine the amount of certain chemical element in food sample but also to identify the form in which given element occurs in given sample. Employment of bespoke and nontargeted speciation methods, with the use of liquid chromatography inductively coupled plasma mass spectrometry (LC/ICP-MS) and complementary techniques, provides more complete picture on the metals and metalloids speciation in food. This review discusses issues concerning speciation analysis of metals and metalloids in food samples with the use of LC/ICP-MS as a leading technique in elemental speciation nowadays and a complimentary technique intended for their identification. © 2020 John Wiley & Sons Ltd. Mass Spec Rev.

Fresh and processed wild Cantharellus cibarius L. growing in West Siberia: food value

Introduction. Cantharellus cibarius L. is a wild mushroom that has been part of human diet for many centuries. However, there is little reliable information about its nutritional value, storage conditions, shelf life, and processing. The research objective was to study the nutritional value of C. cibarius growing in West Siberia, as well as to define its storage and processing conditions. Study objects and methods. The research featured fresh and processed (boiled and salted) wild chanterelles (C. cibarius) obtained from the forests of the Novosibirsk region. The mushrooms were tested for amino acids, fatty acids, nutrients, reducing sugars, trehalose, mannit, glycogen, fiber, mucus, squalene, ash, minerals, vitamins, trypsin inhibitor, chlorides, mesophilic and facultative anaerobes, etc. The samples also underwent sensory evaluation. Results and discussion. The samples of C. cibarius proved to have a high nutritional value. The samples contained 3.6% proteins, including essential amino acids; 3.9% carbohydrates, including sugars and dietary fiber; and 0.7% lipids, including saturated, monounsaturated, and polyunsaturated acids. In addition, C. cibarius appeared to be rich in biologically active substances. It contained trypsin inhibitors that reduce the absorption of protein compounds. Purchasing centers can be recommended to use 70–80% relative air humidity. At 0–2°C, the storage time was five days; at 5–10°C – three days; at 15–20°C – two days; at 20–30°C – one day. Before processing, the mushrooms were washed twice in non-flowing water. C. cibarius also proved to be a valuable raw material for boiled and salted semi-finished products. The optimal boiling time was 5–10 min. Lightly-, medium-, and strong-salted semi-finished mushrooms were ready for consumption after the fermentation was complete, i.e. after day 15, 10, and 3, respectively. Conclusion. Boiled and salted semi-finished products from Siberian C. cibarius demonstrated excellent sensory qualities and can become part of various popular dishes.

A review on cleaner strategies for extraction of chitosan and its application in toxic pollutant removal

Existence of human beings in this world require a cleaner environment, in which, water is the main requirement for living. Owing to the considerable development in civilisation and considerable population explosion, an increase in the contamination of natural water resources by means of non-biodegradable contaminants like heavy metals is observed thereby increasing the need for treatment of water before usage. Despite the existence of specific limits for disposal of heavy metals in water resources, studies still show high contamination of heavy metals in all these water resources. This review provides a brief note on sources and toxicity of different heavy metals in various oxidation states, their effects as well as highlights the numerous available and advanced techniques for heavy metals removal. Of all techniques adsorption is found to be beneficial as it doesn't inculcate any secondary pollutants to the environment. Additionally, this article has investigated the advantages of polymer nanocomposites in adsorption and mainly focused on biopolymer chitosan owing to its abundance in natural environment. The cleaner techniques for the extraction of chitosan and its functionalisation using different types of nanofillers are comprehensively discussed in this review. This article suggests a better alternative for conventional adsorbents as well as aids in remediation of wastes.

Development of sensitive and accurate solid-phase microextraction procedure for preconcentration of As(III) ions in real samples

We synthesized the poly(methyl methacrylate-co-2-aminoethyl methacrylate (PMaema) amphiphilic copolymer in a form of solid phase adsorbent. Then it was used for separation, preconcentration and determination of trace amount of As(III) ions from foods and waters with hydride generation atomic absorption spectrometry. The PMaema was characterized by fourier transform infrared spectrometer and nuclear magnetic resonance spectrometer. The adsorption of As(III) to the PMaema was also supported using computational chemistry studies. The experimental parameters (pH, PMaema amount, adsorption time and ethanol volume) were optimized using a three-level Box-Behnken design with four experimental factors. We observed linear calibration curve for the PMaema amount in the 10-500 ng L-1 range (R2 = 0.9956). Limit of detection, preconcentration factor and sorbent capacity of PMaema were equal to 3.3 ng L-1, 100 and 75.8 mg g-1, respectively. The average recoveries (spiked at 50 ng L-1) changes in the range of 91.5-98.6% with acceptable relative standard deviation less than 4.3%. After validation studies, the method was successfully applied for separation, preconcentration and determination of trace amount of As(III) from foods and waters.

Density Functional Theory Investigation of As(III) S-Adenosylmethionine Methyltransferase

Arsenic is one of the most pervasive environmental toxins. It enters our water and food supply through many different routes, including the burning of fossil fuels, the application of arsenic-based herbicides, and natural sources. Using a density functional theory (DFT) cluster approach, the mechanism of arsenic (III) S-adenosylmethionine methyltransferases and various selenium-containing analogues was investigated. Notably, the methylation of arsenic by arsenic (III) S-adenosylmethionine is proposed to be a way to remove arsenic from contaminated water or soil. From the DFT cluster results, it was found that the selective substitution of the active-site Cys44, Cys72, and Cys174 residues with selenocysteines had a marginal effect on the barrier for CH₃ transfer. Specifically, the average Gibbs activation energy was calculated to be only 4.2 kJ mol^-1 lower than the Gibbs activation energy of 107.4 kJ mol^-1 for the WT enzyme. However, importantly, it was found that with selective mutation, the methylation process becomes considerably more exergonic, where the methylation reaction can be made to be 26.4 kJ mol^-1 more exergonic than the reaction catalyzed by the WT enzyme. Therefore, we propose that the selective substitution of the active-site Cys44, Cys72 and Cys174 residues with selenocysteines could make the process of methylation and volatilization more advantageous for bioremediation.

Arsenic and arsenic speciation in mushrooms from China: A review

Arsenic (As) is a natural environmental contaminant to which humans are usually exposed in water, air, soil, and food. China is a typical high-As region, and also a great contributor of the world production of cultivated edible mushrooms and a region abundant in wild growing edible mushrooms. Mushrooms can accumulate different amounts of As and different As compounds, so potential health risk of As intake may exist to people who use mushrooms with elevated As contents as food or medicine. A systematic literature search was carried out for studies on As and As compounds in mushrooms from China. We compiled existing data from published sources in English or Chinese and provide an updated review of the findings on As in mushrooms associated with environments and health risks. Future perspectives for studies on As in mushrooms have also been discussed.

Analytical Methodologies for the Determination of Organoarsenicals in Edible Marine Species: A Review

Setting regulatory limits for arsenic in food is complicated, owing to the enormous diversity of arsenic metabolism in humans, lack of knowledge about the toxicity of these chemicals, and lack of accurate arsenic speciation data on foodstuffs. Identification and quantification of the toxic arsenic compounds are imperative to understanding the risk associated with exposure to arsenic from dietary intake, which, in turn, underscores the need for speciation analysis of the food. Arsenic speciation in seafood is challenging, owing to its existence in myriads of chemical forms and oxidation states. Interconversions occurring between chemical forms, matrix complexity, lack of standards and certified reference materials, and lack of widely accepted measurement protocols present additional challenges. This review covers the current analytical techniques for diverse arsenic species. The requirement for high-quality arsenic speciation data that is essential for establishing legislation and setting regulatory limits for arsenic in food is explored.

Arsenic speciation in mushrooms using dimensional chromatography coupled to ICP-MS detector

This study concerns total arsenic (TAs) and arsenic species determination in three species of mushrooms collected in Yunnan, China. The purpose of this study was to check concentration level of arsenic in Boletus edulis, Tricholoma matsutake and Suillellus luridus, estimate arsenic bioaccessibility and find out which arsenic species occur in mushrooms to assess if they may pose a threat to human health. An analytical methodology based on ion chromatography (IC) hyphenated to inductively coupled plasma mass spectrometry (ICP-MS) with dynamic reaction cell (DRC) and size exclusion chromatography (SEC) with UV-Vis detection and ICP-DRC-MS detection. Ultrasound assisted extraction (UAE), microwave assisted extraction (MAE) and enzymatic assisted extraction (EAE) were applied. Quantification of As species in extracts was performed by IC/ICP-DRC-MS in the first dimension. Slightly better extraction efficiencies were obtained for MAE (from 75% to 90%) then for UAE. EAE was used for estimation of bioaccessibility by application of a modified BARGE bioaccessibility method (UBM) for in vitro studies. Bioaccessibility values were in the ranges of 73%-102%, 74%-115% and 18%-87% for step 1 (S1), for step 2 (S2) and for step 3 (S3) of EAE, respectively. Extracts obtained after EAE were subjected to SEC-UV-Vis/ICP-DRC-MS analysis as the second dimension. The main signal was obtained in the area of a molecular mass of ∼5 kDa for all mushroom extracts. Monitoring of an ⁵⁰SO⁺ ion confirmed that this signal comes from As-protein. In sample of Boletus edulis additional signal occurred which is classified as unknown As-compound. Both signals require identification with another analytical technique.