A universal method for the speciation analysis of arsenic in various seafood based on microwave-assisted extraction and ion chromatography-inductively coupled plasma mass spectrometry

Bio-accessibility and bio-availability evaluation of each arsenic species existing in various edible seaweeds in vitro and in vivo for arsenic risk assessment

Seaweeds consumption is one of main internal exposure sources of arsenic for human. However, the absence of representative bio-availabilities of arsenic species makes the accurate assessment of arsenic health risk originating from seaweeds consumption impossible. Herein, the arsenic species in various seaweeds collected from Fujian of China were investigated, and the bio-accessibilities/bio-availabilities of arsenic species existing in seaweeds were evaluated in vitro and in vivo. Results revealed that in vitro bio-availabilities of arsenic species presenting in seaweeds, which obtained with Caco-2 cells, were lower than those of pure arsenic standards, and varied with order of inorganic arsenic (iAs) > dimethylarsinic acid (DMA) ≈ arsenobetaine (AsB) > arsenosugars. During gastrointestinal digestion of mice, As5+ was partly methylated into monomethylarsonic acid (MMA) and DMA, which makes the in vivo bioavailability of iAs (⁓31.8 %) obtained with mouse metabolic experiment is much higher than its in vitro bio-availability (⁓10.3 %). The in vivo bio-availabilities of DMA and total arsenic (tAs) are similar to their in vitro bio-availabilities. As the dominant arsenic species in most seaweeds, arsenosugars have an ⁓0.0 % of in vivo bioavailability and only a ⁓3.7 % of in vitro bioavailability. The simulated calculation of target hazard quotient (THQ) and target cancer risk (TR) revealed that the arsenic risk originating from seaweeds was greatly degraded by taking into consideration of arsenic species and bio-availabilities, and all seaweeds collected from Fujian are safety for consumption. The simulated calculation also revealed that arsenic risk of seaweeds can be also more accurately assessed based on tAs together with bioavailability, which provides a simple but accurate and protective method for the risk assessment of arsenic originating from seaweeds. Our work provides the possible representative bio-availabilities of arsenic species presenting in seaweeds for accurately assessing arsenic risk of seaweeds, and novel insights into the bio-availabilities of arsenic in animal.

Analysis of environmental pollutants using ion chromatography coupled with mass spectrometry: A review

The rise of emerging pollutants in the current environment and requirements of trace analysis in complex substrates pose challenges to modern analytical techniques. Ion chromatography coupled with mass spectrometry (IC-MS) is the preferred tool for analyzing emerging pollutants due to its excellent separation ability for polar and ionic compounds with small molecular weight and high detection sensitivity and selectivity. This paper reviews the progress of sample preparation and ion-exchange IC-MS methods in the analysis of several major categories of environmental polar and ionic pollutants including perchlorate, inorganic and organic phosphorus compounds, metalloids and heavy metals, polar pesticides, and disinfection by-products in past two decades. The comparison of various methods to reduce the influence of matrix effect and improve the accuracy and sensitivity of analysis are emphasized throughout the process from sample preparation to instrumental analysis. Furthermore, the human health risks of these pollutants in the environment with natural concentration levels in different environmental medias are also briefly discussed to raise public attention. Finally, the future challenges of IC-MS for analysis of environmental pollutants are briefly discussed.

A broad-applicability method for mercury speciation in various seafoods using microwave-assisted extraction and ion chromatography-inductively coupled plasma mass spectrometry

Almost all marine organisms contain both inorganic and organic mercury, and thus it is extremely important to determine mercury species in seafood to objectively and scientifically assess the health risk posed by mercury. We herein developed a broad-applicability microwave-assisted extraction method and a robust ion chromatography-inductively coupled plasma mass spectrometry (IC-ICP-MS) method for the speciation analysis of mercury in various seafood samples including seaweeds, fishes and shellfishes. The extraction method has broad adaptability, it can be used to simultaneously extract mercury species from various seafood samples including seaweeds, fishes and shellfishes without altering the chemical species of mercury, with an extraction efficiency >90%. Especially, the seafood extract obtained with the extraction method can be directly used for the following IC-ICP-MS determination of mercury species without additional pretreatment. The IC-ICP-MS method used low-cost cation guard columns as the separation column, and has an instrument detection limit of 0.02-0.05 ng mL^-1 for Hg²⁺, CH₃Hg⁺ and C₂H₅Hg⁺. The developed extraction and IC-ICP-MS methods have been successfully used to determine Hg²⁺, CH₃Hg⁺ and C₂H₅Hg⁺ in various seaweeds, fishes and shellfishes without the matrix effect, with a method detection limit of 2.4-6.0 ng g^-1 dried weight, a recovery of 92-105%, and a relative standard deviation (RSD, n = 5) of less than or equal to 6%. The success of this study offers a reliable and universal approach for the speciation analysis of mercury in seafood, which may provide the database for objectively assessing the health risks of mercury in seafood and ensuring the safety of consumption of seafood.

Characterization and Quantification of Arsenic Species in Foodstuffs of Plant Origin by HPLC/ICP-MS

Arsenic is a well-known carcinogenic, mutagenic and toxic element and occurs in the environment both as inorganic arsenic (iAs) and organoarsenical compounds (oAsCs). Since the toxicity of arsenic compounds depends on their chemical form, the identification and determination of arsenic species are essential. Recently, the European Food Safety Authority, following the European Commission request, published a report on chronic dietary exposure to iAs and recommended the development and validation of analytical methods with adequate sensitivity and refined extraction procedures for this determination. Moreover, the authority called upon new arsenic speciation data for complex food matrices such as seaweeds, grains and grain-based products. Looking at this context, an optimized, sensitive and fast analytical method using high performance liquid chromatography followed by inductively coupled plasma-mass spectrometry (HPLC/ICP-MS) was developed for the determination of iAs (sum of arsenite-As^III and arsenate-As^V) and the most relevant oAsCs, arsenobetaine, dimethylarsinic acid and monomethylarsonic acid. The method was validated with satisfactory results in terms of linearity, sensitivity, selectivity, precision, recovery, uncertainty, ruggedness and matrix effect, and then successfully applied for the analysis of several matrices, i.e., processed and unprocessed cereal and cereal products, fruits, vegetables, legumes, seaweeds, nuts and seeds. The results obtained indicate that not only seaweed and rice matrices but also many cereals, legumes and plant-based foods for infants and young children contain significant concentrations of iAs and oAsCs. These findings contribute to the data collection necessary to assess the role of these matrices in the total arsenic exposure and if specific maximum limits have to be established.

Metabolomics Analysis of Chronic Exposure to Dimethylarsenic Acid in Mice and Toxicity Assessment of Organic Arsenic in Food

Dimethylarsenic acid is a natural organic arsenic in seafood and one of the important metabolites of inorganic arsenic, which is generally considered to have low or no toxicity. However, due to the controversy of the toxicity of organic arsenic, the food safety standard of organic arsenic has not been established until now, and the effects of organic arsenic on chronic toxicity and the overall metabolic level of animals are rarely reported. In our study, 64 female C57BL/6 mice were exposed to different concentrations of dimethylarsenic acid with water intake. Fifteen metabolites in serum were detected to be altered with the increase of arsenic concentration and exposure time. Dimethylarsenic acid exposure significantly affected the overall metabolic level of mice, and the related effects were not recovered shortly after the suspension of arsenic intake. Although arsenic was excreted largely in urine and feces, continued dimethylarsenic acid exposure could still lead to arsenic accumulation in the liver and kidneys and cause mild nephritis in mice.

Soluble arsenic species in total suspended particles and their health risk and origin implication: A case study in Taiyuan, China

The inhalation is one of important exposure ways to arsenic. Traditionally, the health risk of arsenic exposure from particulate matter (PM) was assessed by using total arsenic, which may erroneously estimate the health risk of arsenic since the toxicity of arsenic depends on its chemical species and not all arsenic in PM is bio-accessible. Herein, total suspended particles (TSP) were collected from Taiyuan in China during whole year of 2018, and the species and concentrations of arsenic in TSP were investigated in order to more accurately assess the health risk of arsenic exposure from TSP and evaluate the possible sources of arsenic in TSP. Total arsenic varied within 1.16-28.4 ng/m³ with a mean value of 7.40 ng/m³, which exceeded the standard limit of China (6 ng/m³). Two arsenic species, As⁵⁺ and As³⁺, were detected out in soluble fractions of TSP, with As⁵⁺ as dominant species. Total arsenic, soluble arsenic and soluble As⁵⁺ in TSP revealed closed correlation each other, indicating that they may originate from similar anthropogenic and crust sources. Soluble As³⁺ showed no obvious correlations with total arsenic, implying that soluble As³⁺ has different dominant sources. The ratio of As⁵⁺/As³⁺ significantly varied within 1.08-32.5 and the percentages of soluble arsenic in total arsenic varied within 50%-93%, implying that arsenic in TSP of Taiyuan has multiple sources and none of them stably dominated during 2018. Non-carcinogenic risk and carcinogenic risk indicators calculated with soluble arsenic species showed significant difference to that calculated with total arsenic or soluble arsenic when TSP contained equivalent As⁵⁺ and As³⁺, verifying that it is necessary and more accurate to assess the health risk of arsenic exposure from TSP by using soluble arsenic species, rather than total arsenic or soluble arsenic.

Highly selective and sensitive detection of arsenite ions(III) using a novel tetraphenylimidazole-based probe

More than 200 million people in the world are exposed to areas where the arsenic concentration exceeds the limit allowed for living species, which urges researchers to develop low-cost methods for the selective and fast detection of arsenic ions in environmental samples. Herein, we report a novel tetraphenylimidazole-based probe (TBAB) functionalized with a Schiff base for sensing and detecting arsenic ions in aqueous media. Upon the addition of arsenic ions, an obvious fluorescence change from faint yellow to green was observed visible to the naked eye. The probe can detect arsenic selectively in the presence of interfering substances, with a lower detection limit than 0.7 ppb, a value which is far lower than the limit set by the WHO. A detailed mechanism revealed that the chelation of TBAB with arsenic activated the AIE characteristic, leading to the enhanced fluorescence, which was verified by Job's plot experiment and HRMS. Its practicality was further validated by the analysis of real water samples, demonstrating its potential application for on-site detection and biological application.

In vitro bio-accessibility and distribution characteristic of each arsenic species in different fishes and shellfishes/shrimps collected from Fujian of China

It is very important to consider the bio-accessibilities and concentrations of each arsenic species, not total arsenic, in seafood in order to accurately assess internal exposure level and health risk of arsenic from seafood. Herein, the concentrations and in vitro bio-accessibilities of each arsenic species in various fishes and shellfishes/shrimps were extensively investigated. Experimental results showed that arsenic species and contents in shellfishes/fishes remarkably varied with the difference of fish/shellfish species or individuals and sampling area, and arsenobetaine (AsB) is dominant arsenic species for fishes and shellfishes/shrimps. Different arsenic species in the same fish/shellfish have quite different bio-accessibilities, and the bio-accessibilities of each arsenic species also varied with fish/shellfish species or individuals. As³⁺ in fishes/shellfishes was partly oxidized to form As⁵⁺ during gastrointestinal digestion, and thus it is more reasonable and practicable to evaluate the bio-accessibilities of inorganic arsenic (iAs, total As³⁺ and As⁵⁺), not individual As³⁺ and As⁵⁺. Fishes and shellfishes/shrimps have similar bio-accessibilities of iAs, AsB and total arsenic, whereas have different bio-accessibilities of MMA (monomethylarsonic acid), DMA (dimethylarsinic acid), and two un-identified arsenic (Ui-As1 and Ui-As2). The results of this study provided a valuable knowledge for accurately assessing the health risk of arsenic in seafood.

A new method for highly efficient separation and determination of arsenic species in natural water using silica modified with polyamines

A simple and highly efficient method for the determination of highly toxic arsenic species using non-covalently aminated silica is proposed. The polyamines including poly(hexamethyleneguanidine), poly(4,9-dioxadodecane-1,12-guanidine), hexadimethrine, and poly(diallyldimethylammonium) were tested as silica modifiers. The prepared adsorbents allow effective preconcentration of anionic species of arsenic from aqueous solutions. It was found that As(V) can be quantitatively extracted from solutions at pH 4.5-7.0 by the anion exchange mechanism in less than 5 min, while neutral at this pH As(III) was not adsorbed at these conditions. A reaction with 2,3-dimercapto-1-propanesulphonic acid, which resulted in the formation of the negatively charged complex of As(III) with adsorbents was used for its quantitative extraction from solutions with a pH of 3.5-6.5. A system of two cartridges filled with poly(diallyldimethylammonium) modified silica and the on-line reaction of As(III) with 2,3-dimercapto-1-propanesulphonic acid proceeding between the cartridges was used for separate preconcentration and determination of As(V) and As(III) at pH 5. The proposed method was used for four-year monitoring of natural water pollution by arsenic in the area of residence of the indigenous peoples of Tyva Republic (Russia).