Sample pre-treatment and extraction methods that are crucial to arsenic speciation in algae and aquatic plants

Bioaccumulation of arsenic in fish (Labeo rohita) in presence of periphyton: ameliorative effect on oxidative stress, physiological condition, immune response and risk assessment

The present study explores the use of periphyton to ameliorate toxic properties of arsenic (As) to Labeo rohita and also assesses the human food safety aspects. Fish were introduced to arsenite [As(III)] contaminated water (0.3 and 3 mg/L) along with periphyton. Biochemical, physiological and immunological parameters, including gene expression, were assessed after 30 days of exposure. Periphyton incorporation significantly improved (p < 0.05) the adverse effects of As on respiration, NH3 excretion and brain AChE activity by reducing oxidative stress and As bioaccumulation. The presence of periphyton in As(III) exposed fish (3 mg/L) increased the immune response (Immunoglobulin M and Complement C3) in the serum and the regulation of the respective immune genes in the anterior kidney was found to be similar to the control. A speciation study using LC-ICP-MS confirmed the high accumulation of As by periphyton (5.0-31.9 μg/g) as arsenate [As (V)], resulting in a lower amount of As in fish muscle. The calculated human health risk indices, Target Hazard Quotient (THQ) and Target Cancer risk (TCR) indicate that fish grown in periphyton-treated water may lower the human health risks associated with As. The study signifies the importance of periphyton-based aquaculture systems in As contaminated regions for safe fish production with enhanced yield.

Influence of extracellular polymeric substances on arsenic bioaccumulation and biotransformation in biofilms

It is well recognized that biofilms can biosorb and biotransform heavy metals in aquatic environments. However, the effects of extracellular polymeric substance (EPS) on inorganic arsenic (As) bioaccumulation and biotransformation in biofilms are still unrevealed and need to be investigated. In order to explore the above scientific issues, the As accumulation and speciation in EPS-containing or EPS-free biofilms and growth medium under As(V)/As(III) exposure conditions were measured. After the removal of EPS, the amount of As uptake (Asup) and As adsorption (Asad) in biofilms were significantly reduced, no matter whether exposed to As(V) or As(III). FTIR analysis further suggested that the interaction between these functional groups with As was limited after the removal of EPS. In the EPS-containing biofilms, the Asad was mainly As(V) with low toxicity. However, after the removal of EPS, the Asad was mainly As(III) with high fluidity, and no methylated As was found. Moreover, the removal of EPS inhibited As(III) oxidation and methylation by biofilms, resulting in the decrease of As(V) and methylated As in the growth medium. The findings of this study emphasized the essential impact of EPS on the biosorption and biotransformation of As in biofilms. This study provides a unique understanding of the role of biofilms in As biogeochemical cycle, and water quality purification function in water environments.

Trace metal content from holopelagic Sargassum spp. sampled in the tropical North Atlantic Ocean: Emphasis on spatial variation of arsenic and phosphorus

We document for the first time, the spatial distribution at basin scale (North tropical Atlantic Ocean) of As, P and trace metal (TM) concentrations in the three morphotypes belonging to the two holopelagic species Sargassum natans and S. fluitans and three morphotypes: S. natans VIII, S. natans I and S. fluitans III. These samples collected in the North equatorial current (NEC) and in the subtropical Sargasso Sea (sSS) (∼25°N, 60°W) were also compared to coastal samples collected downwind Guadeloupe Island and on the strand of Martinique (mangrove and beach). Along the studied zonal oceanic transect, the highest values of As (range 120-240 μg g-1, dry weight, dw) were found in the sSS area where primary production is highly limited by phosphorus. At these stations, the P content of Sargassum spp. was minimal (range 500-1000 μg g-1, dw) as well as the content in Cd and Zn known for their nutrient-like oceanic behaviors and distributions very similar to P. This illustrates for the first time in the natural environment, the higher bioaccumulation of arsenic in Sargassum spp. in P-limiting conditions which is due to the competition in the phosphate transporter between arsenate and phosphate. As compared to samples collected at sea, the Sargassum spp. collected in the strand of Martinique had (1) lower As concentrations (typical range 30-45 μg g-1, dw) and (2) much higher Al, Fe, Mn, Cr and Co concentrations, showing a certain ability of Sargassum spp. to be depurated of its As content in the coastal zone following competitive exchange with terrigenous metals.

Industry chain and challenges of microalgal food industry-a review

Currently, the whole world is facing hunger due to the increase in the global population and the rising level of food consumption. Unfortunately, the impact of environmental, climate, and political issues on agriculture has resulted in limited global food resources. Thus, it is important to develop new food sources that are environmentally friendly and not subject to climate or space limitations. Microalgae represent a potential source of nutrients and bioactive components for a wide range of high-value products. Advances in cultivation and genetic engineering techniques provide prospective approaches to widen their application for food. However, there are currently problems in the microalgae food industry in terms of assessing nutritional value, selecting processes for microalgae culture, obtaining suitable commercial strains of microalgae, etc. Additionally, the limitations of real data of market opportunities for microalgae make it difficult to assess their actual potential and to develop a better industrial chain. This review addresses the current status of the microalgae food industry, the process of commercializing microalgae food and breeding methods. Current research progress in addressing the limitations of microalgae industrialization and future prospects for developing microalgae food products are discussed.

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.

Epiphytic bacterial community enhances arsenic uptake and reduction by Myriophyllum verticillatum

Microbes play an important role in the biotransformation of arsenic (As) speciation in various environments. Nevertheless, whether epiphytic bacteria that attached on submerged macrophytes have the potential to influence As speciation still remains unclear. In this study, sterile or nonsterile Myriophyllum verticillatum was cultured with arsenite (As(III)) or arsenate (As(V)) to investigate the impact of epiphytic bacterial community on As uptake, transformation, and efflux. Results showed that both sterile and nonsterile M. verticillatum did not display substantial As(III) oxidation, suggesting that neither M. verticillatum nor epiphytic bacterial community has the capacities of As(III) oxidation. However, sterile M. verticillatum exhibited capacity for As(V) reduction, and the presence of epiphytic bacterial community substantially enhanced the proportions of As(III) in the medium (from 39.91 to 98.44%), indicating that epiphytic bacterial community contributes significantly to As(V) reduction in the medium. The presence of epiphytic bacterial community elevated As accumulation (by up to 2.06-fold) in plants when exposed to As(V). Results also showed that epiphytic bacterial community contributed little to As(III) efflux. Quantitative PCR of As metabolism genes revealed the dominance of the respiratory As(V) reductase genes (arrA) in epiphytic bacterial community, which might play a significant role in As(V) reduction in aquatic environments. Phylogenetic analysis of the arrA genes revealed the widely distribution and diversity of As(V)-respiring bacteria. These results highlighted the substantial impact of the epiphytic bacterial community associated with submerged aquatic macrophytes on As biogeochemistry in wetland and water environments.

Stability of Arsenic Species During Bioaccessibility Assessment Using the In Vitro UBM and HPLC-ICP-MS Detection

The stability of four major arsenic (As) species during application of the BARGE (Bioaccessibility Research Group of Europe) unified bioaccessibility method (UBM) has been assessed. The concentrations of As species in the UBM gastric and gastro-intestinal (gastric + intestinal) phases were determined using HPLC-ICP-MS whilst the total As content in the samples was determined using ICP-MS alone. The arsenic species studied were arsenite As(III), arsenate As(V), dimethylarsinic acid (DMA) and monomethylarsonic acid (MMA). These species were separated in 10 min using an anion exchange column (Hamilton PRP-X100) with a mobile phase containing 20 mmol L^-1 NH₄H₂PO₄/1% methanol (pH 6.0). The recoveries of arsenic species spiked into the gastric and gastro-intestinal fluids were in the range 90-108%. No interconversion between As species was observed as a result of applying the BARGE UBM, which is a particularly important finding for the reliability of As(III) measurements. The accuracy of the BARGE UBM for in vitro extractable As(V) was verified using British Geological Survey (BGS) guidance material 102 (an ironstone soil). For a commercial rice sample, the bioaccessibility sequence of As was DMA > As(III) > As(V) for the gastric phase and As(III) > DMA > As(V) for the gastro-intestinal phase.

Arsenic species and their transformation pathways in marine plants. Usefulness of advanced hyphenated techniques HPLC/ICP-MS and UPLC/ESI-MS/MS in arsenic species analysis

The growing popularity of algae as a foodstuff around the world raises concern for the safety of this food type with respect to arsenic content in algae. The need for determination of total arsenic content and arsenic speciation in algae food has become an important issue. In this paper we have developed a complete analytical procedure for arsenic determination in algae products comprised of 1) total arsenic (tAs) determination in native algae samples after digestion, 2) extraction of As species with the use of two extraction methods with three extracting agents, 3) extracted total arsenic (extracted tAs) determination in algae extracts, 4) bespoke As speciation, 4) mass balance estimation based on extracted tAs and bespoke As speciation results, 5) unknown arsenic (uAs) species identification. Two advanced hyphenated techniques, HPLC/ICP-MS and UPLC/ESI-MS/MS, were employed along with the HPLC/ICP-MS method validation. Total As content in edible algae samples was found to range from (19.28 ± 0.45) mg kg^-1 up to (72.6 ± 2.7) mg kg^-1. Bespoke arsenic speciation of edible algae samples has revealed the presence of some known inorganic and simple organic As compounds such as As(III) from <LOD to (8.97 ± 0.59) mg kg^-1, As(V) from <LOD to (5.95 ± 0.29) mg kg^-1 and DMA from <LOD to (0.766 ± 0.040) mg kg^-1. Mass balance calculation carried out on the basis of tAs and bespoke As speciation results has shown that the amount of unknown As species in edible algae samples varied from 28% to 100% of extracted tAs. Identification of uAs species in edible algae samples has shown the presence of a high variety of As-sugars (12 compounds) and confirmed the presence of simple inorganic and organic As species such as As(V) and DMA along with 8 more simple organic As compounds. The results obtained in this study have confirmed that the high amounts of tAs do not correspond to the toxicity of algae based food due to the lack of the inorganic As in the tested samples.

Influence of epiphytic bacteria on arsenic metabolism in Hydrilla verticillata

Microbial assemblages such as biofilms around aquatic plants play a major role in arsenic (As) cycling, which has often been overlooked in previous studies. In this study, arsenite (As(III))-oxidizing, arsenate (As(V))-reducing and As(III)-methylating bacteria were found to coexist in the phyllosphere of Hydrilla verticillata, and their relative activities were shown to determine As speciation, accumulation and efflux. When exposed to As(III), As(III) oxidation was not observed in treatment H(III)-B, whereas treatment H(III)+B showed a significant As(III) oxidation ability, thereby indicating that epiphytic bacteria displayed a substantial As(III) oxidation ability. When exposed to As(V), the medium only contained 5.89% As(III) after 48 h of treatment H(V)-B, while an As(III) content of 86.72% was observed after treatment H(V)+B, thereby indicating that the elevated As(III) in the medium probably originated from As(V) reduction by epiphytic bacteria. Our data also indicated that oxidizing bacteria decreased the As accumulation (by approximately 64.44% compared with that of treatment H(III)-B) in plants, while reducing bacteria played a critical role in increasing As accumulation (by approximately 3.31-fold compared with that of treatment H(V)-B) in plants. Regardless of whether As(III) or As(V) was supplied, As(III) was dominant in the plant tissue (over 75%). Furthermore, the presence of epiphytic bacteria enhanced As efflux by approximately 9-fold. Metagenomic analysis revealed highly diverse As metabolism genes in epiphytic bacterial community, particularly those related to energetic metabolism (aioAB), and As resistance (arsABCR, acr3, arsM). Phylogenetic analysis of As metabolism genes revealed evidence of both vertical inheritance and horizontal gene transfer, which might have contributed to the evolution of the As metabolism genes. Taken together, our research suggested that the diversity of As metabolism genes in epiphytic bacterial community is associated with aquatic submerged macrophytes which may play an important role in As biogeochemistry in aquatic environments.

Arsenosugar standards extracted from algae: Isolation, characterization and use for identification and quantification purposes

Sulfate (SO4-sug) and sulfonate (SO3-sug) arsenosugar standard solutions were obtained using preparative liquid chromatography. Several commercial algae samples were characterized (total contents and speciation) to select the most appropriate in relation to their arsenosugar contents. Water extracts from the selected sample (Fucus vesiculosus) were fractionated using a Hamilton PRP-X100 preparative column, and the presence of arsenic species in the isolated fractions was ascertained by IC-ICP-MS. Two of the fractions successfully presented only one arsenic species corresponding to sulfate and sulfonate arsenosugars at suitable concentrations. To unequivocally confirm the presence of both compounds, high-resolution mass spectrometry (ESI-TOF/MS) was used and the exact mass determined with errors lower than 0.5 ppm. The standard solutions obtained were successfully used to identify and quantify SO4-sug and SO3-sug in several edible algae samples purchased in local market. Total arsenic content for analyzed samples ranged from 34 to 57 mg kg-1, concentration values found for SO3-sug ranged from 5 to 36 mg As kg-1 and SO4-sug was only found in fucus with a concentration of 9.3 mg As kg-1.

Speciation analysis of arsenic in seafood and seaweed: Part I-evaluation and optimization of methods

Several extraction and chromatographic methods were evaluated to identify optimum conditions for arsenic speciation analysis in seafood and seaweed. The extraction systems, which include aqueous, aqueous-organic, acidic, basic, and enzymatic solutions, were examined for their efficiency in extracting arsenic from finfish, crustaceans, molluscs, and seaweed keeping the chemical forms of the native arsenicals intact. While dilute solutions of nitric acid, hydrochloric acid, and tetramethylammonium hydroxide (TMAH) extract high fractions of arsenic from most of the matrices, the extractants oxidized arsenite (As³⁺) to arsenate (As⁵⁺) and converted some arsenosugars and non-polar arsenicals to known and/or unknown forms. Hot water (90 °C) effectively maintained the integrity of the native arsenic species and enabled analysis of the extracts with no further manipulation than filtration and dilution. Stepwise extraction of water-soluble and non-polar arsenic with hot water and a mixture of dichloromethane and methanol, respectively, resulted in sufficiently quantitative (> 75%) arsenic extraction from seafood and seaweed. Anion and cation exchange chromatographic methods were optimized for separation and quantitation of the arsenicals extracted into hot water. The non-polar arsenicals were collectively determined after digesting the extract in acid. The application of the optimum extraction and chromatographic conditions was demonstrated by analyzing certified reference materials of tuna fish tissue (BCR 627), lobster hepatopancreas (TORT-2) and oyster tissue (SRM 1566b), and a sample of hijiki seaweed. For all the matrices, good agreement (80-92%) was found between the total water-soluble arsenic and the sum of the concentrations of the chromatographed species. Limits of quantification (LOQ) were in the range 4-11 ng g^-1 for 16 arsenicals.

Determination of inorganic arsenic in algae using bromine halogenation and on-line nonpolar solid phase extraction followed by hydride generation atomic fluorescence spectrometry

Accurate, stable and fast analysis of toxic inorganic arsenic (iAs) in complicated and arsenosugar-rich algae matrix is always a challenge. Herein, a novel analytical method for iAs in algae was reported, using bromine halogenation and on-line nonpolar solid phase extraction (SPE) followed by hydride generation atomic fluorescence spectrometry (HG-AFS). The separation of iAs from algae was first performed by nonpolar SPE sorbent using Br^- for arsenic halogenation. Algae samples were extracted with 1% perchloric acid. Then, 1.5mL extract was reduced by 1% thiourea, and simultaneously reacted (for 30min) with 50μL of 10% KBr for converting iAs to AsBr₃ after adding 3.5mL of 70% HCl to 5mL. A polystyrene (PS) resin cartridge was employed to retain arsenicals, which were hydrolyzed, eluted from the PS resin with H₂O, and categorized as iAs. The total iAs was quantified by HG-AFS. Under optimum conditions, the spiked recoveries of iAs in real algae samples were in the 82-96% range, and the method achieved a desirable limit of detection of 3μgkg^-1. The inter-day relative standard deviations were 4.5% and 4.1% for spiked 100 and 500μgkg^-1 respectively, which proved acceptable for this method. For real algae samples analysis, the highest presence of iAs was found in sargassum fusiforme, followed by kelp, seaweed and laver.

Inorganic Arsenic Determination in Food: A Review of Analytical Proposals and Quality Assessment Over the Last Six Years

Here we review recent developments in analytical proposals for the assessment of inorganic arsenic (iAs) content in food products. Interest in the determination of iAs in products for human consumption such as food commodities, wine, and seaweed among others is fueled by the wide recognition of its toxic effects on humans, even at low concentrations. Currently, the need for robust and reliable analytical methods is recognized by various international safety and health agencies, and by organizations in charge of establishing acceptable tolerance levels of iAs in food. This review summarizes the state of the art of analytical methods while highlighting tools for the assessment of quality assessment of the results, such as the production and evaluation of certified reference materials (CRMs) and the availability of specific proficiency testing (PT) programmes. Because the number of studies dedicated to the subject of this review has increased considerably over recent years, the sources consulted and cited here are limited to those from 2010 to the end of 2015.

New trends in sample preparation techniques for environmental analysis

Environmental samples include a wide variety of complex matrices, with low concentrations of analytes and presence of several interferences. Sample preparation is a critical step and the main source of uncertainties in the analysis of environmental samples, and it is usually laborious, high cost, time consuming, and polluting. In this context, there is increasing interest in developing faster, cost-effective, and environmentally friendly sample preparation techniques. Recently, new methods have been developed and optimized in order to miniaturize extraction steps, to reduce solvent consumption or become solventless, and to automate systems. This review attempts to present an overview of the fundamentals, procedure, and application of the most recently developed sample preparation techniques for the extraction, cleanup, and concentration of organic pollutants from environmental samples. These techniques include: solid phase microextraction, on-line solid phase extraction, microextraction by packed sorbent, dispersive liquid-liquid microextraction, and QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe).

Enzyme-assisted extraction and liquid chromatography mass spectrometry for the determination of arsenic species in chicken meat

Chicken is the most consumed meat in North America. Concentrations of arsenic in chicken range from μg kg(-1) to mg kg(-1). However, little is known about the speciation of arsenic in chicken meat. The objective of this research was to develop a method enabling determination of arsenic species in chicken breast muscle. We report here enzyme-enhanced extraction of arsenic species from chicken meat, separation using anion exchange chromatography (HPLC), and simultaneous detection with both inductively coupled plasma mass spectrometry (ICPMS) and electrospray ionization tandem mass spectrometry (ESIMS). We compared the extraction of arsenic species using several proteolytic enzymes: bromelain, papain, pepsin, proteinase K, and trypsin. With the use of papain-assisted extraction, 10 arsenic species were extracted and detected, as compared to 8 detectable arsenic species in the water/methanol extract. The overall extraction efficiency was also improved using a combination of ultrasonication and papain digestion, as compared to the conventional water/methanol extraction. Detection limits were in the range of 1.0-1.8 μg arsenic per kg chicken breast meat (dry weight) for seven arsenic species: arsenobetaine (AsB), inorganic arsenite (As(III)), dimethylarsinic acid (DMA), monomethylarsonic acid (MMA), inorganic arsenate (As(V)), 3-nitro-4-hydroxyphenylarsonic acid (Roxarsone), and N-acetyl-4-hydroxy-m-arsanilic acid (NAHAA). Analysis of breast meat samples from six chickens receiving feed containing Roxarsone showed the presence of (mean±standard deviation μg kg(-1)) AsB (107±4), As(III) (113±7), As(V) (7±2), MMA (51±5), DMA (64±6), Roxarsone (18±1), and four unidentified arsenic species (approximate concentration 1-10 μg kg(-1)).

Stability of toxic arsenic species and arsenosugars found in the dry alga Hijiki and its water extracts

The achievement of reliable results in speciation analysis requires not only sensitive techniques but also sureness of species stability. Therefore, it is necessary to carry out stability studies because it is important to know with absolute certainty that there is not any species transformation during sample treatment and/or storage. Although several procedures have been recommended for the preservation of species integrity, there is no general agreement, as arsenic species stability depends on the sample matrix, the concentration level and the sample treatment procedure, so it is necessary to assess the arsenic species stability for each case. Thus, the present paper reports the stability tests of arsenic species carried out on the commercially available edible alga Hijiki (Hizikia fusiformis), from Japan, in both the dry sample and its water extracts, which were stored in amber glass and polystyrene containers at -18 and +4°C in the dark. Extractions were carried out with deionized water by microwave-assisted extraction, at a temperature of 90°C and three extraction steps of 5 min each, whereas arsenic speciation analysis was performed by anion exchange high performance liquid chromatography-photo-oxidation-hydride generation-atomic fluorescence spectrometry. The results obtained for the dry alga showed that the arsenic species present in it (arsenate (As(V)), dimethylarsinic acid (DMA) and the arsenosugars glycerol (Gly-sug), phosphate (PO4-sug), sulfonate (SO3-sug) and sulfate (SO4-sug)) were stable for at least 12 months when the sample was stored in polystyrene containers at +20°C in the dark. Regarding water extracts, the best storage conditions consisted of the use of polystyrene containers and a temperature of +4°C, for a maximum storage time of seven days. Therefore, the immediate analysis of Hijiki water extracts would not be necessary, and they could be stored for one week before analysis, ensuring arsenic species stability. This information about species integrity in extracts is especially useful when the sample treatment for arsenic species extraction is time-consuming.

Review of remediation techniques for arsenic (As) contamination: a novel approach utilizing bio-organisms

Arsenic (As) contamination has recently become a worldwide problem, as it is found to be widespread not only in drinking water but also in various foodstuffs. Because of the high toxicity, As contamination poses a serious risk to human health and ecological system. To cope with this problem, a great deal of effort have been made to account for the mechanisms of As mineral formation and accumulation by some plants and aquatic organisms exposed to the high level of As. Hence, bio-remediation is now considered an effective and potent approach to breakdown As contamination. In this review, we provide up-to-date knowledge on how biological tools (such as plants for phytoremediation and to some extent microorganisms) can be used to help resolve the effects of As problems on the Earth's environment.

LC-ICP-MS analysis of arsenic compounds in dominant seaweeds from the Thermaikos Gulf (Northern Aegean Sea, Greece)

The content of total arsenic and arsenic compounds in the dominant seaweed species in the Thermaikos Gulf, Northern Aegean Sea was determined in samples collected in different seasons. Total arsenic was determined by acid digestion followed by ICP-MS. Arsenic speciation was analyzed by water extraction followed by LC-ICP-MS. Total arsenic concentrations in the seaweeds ranged from 1.39 to 55.0 mg kg(-1). Cystoseira species and Codium fragile showed the highest total As contents, while Ulva species (U. intestinalis, U. rigida,U. fasciata) had the lowest Arsenosugars, the most common arsenic species in seaweeds, were found in all samples, and glycerol-arsenosugar was the most common form; however, phosphate-arsenosugar and sulfate-arsenosugar were also present. Inorganic arsenic was measured in seven algae species and detected in another. Arsenate was the most abundant species in Cystoseira barbata (27.0 mg kg(-1)). Arsenobetaine was measured in only one sample. Methylated arsenic species were measured at very low concentrations. The information should contribute to further understanding the presence of arsenic compounds in dominant seaweeds from the Thermaikos Gulf.

Sample preparation for arsenic speciation in terrestrial plants--a review

Arsenic is an element widely present in nature. Additionally, it may be found as different species in several matrices and therefore it is one of the target elements in chemical speciation. Although the number of studies in terrestrial plants is low, compared to matrices such as fish or urine, this number is raising due to the fact that this type of matrix are closely related to the human food chain. In speciation analysis, sample preparation is a critical step and several extraction procedures present drawbacks. In this review, papers dealing with extraction procedures, analytical methods, and studies of species conservation in plants cultivated in terrestrial environment are critically discussed. Analytical procedures based on extractions using water or diluted acid solutions associated with HPLC-ICP-MS are good alternatives, owing to their versatility and sensitivity, even though less expensive strategies are shown as feasible choices.

Occurrence of arsenic species in algae and freshwater plants of an extreme arid region in northern Chile, the Loa River Basin

This study reports data on arsenic speciation in two green algae species (Cladophora sp. and Chara sp.) and in five aquatic plants (Azolla sp., Myriophyllum aquaticum, Phylloscirpus cf. desserticola, Potamogeton pectinatus, Ruppia filifolia and Zannichellia palustris) from the Loa River Basin in the Atacama Desert (northern Chile). Arsenic content was measured by Mass spectrometry coupled with Inductively Coupled Plasma (ICP-MS), after acidic digestion. Liquid chromatography coupled to ICP-MS was used for arsenic speciation, using both anionic and cationic chromatographic exchange systems. Inorganic arsenic compounds were the main arsenic species measured in all samples. The main arsenic species in the extracts of freshwater algae and plants were arsenite and arsenate, whereas glycerol-arsenosugar (gly-sug), dimethylarsinic acid (DMA) and methylarsonic acid (MA) were present only as minor constituents. Of the samples studied, algae species accumulated more arsenic than aquatic plants. Total arsenic content ranged from 182 to 11100 and from 20 to 248 mg As kg(-1) (d.w.) in algae and freshwater plants, respectively. In comparison with As concentration in water samples, there was hyper-accumulation (>0.1% d.w.) in Cladophora sp.

Determination of water-soluble arsenic compounds in commercial edible seaweed by LC-ICPMS

This paper reports arsenic speciation in edible seaweed (from the Galician coast, northwestern Spain) produced for human consumption. Chondrus crispus , Porphyra purpurea , Ulva rigida , Laminaria ochroleuca , Laminaria saccharina , and Undaria pinnatifida were analyzed. The study focused on arsenosugars, the most frequently occurring arsenic species in algae. As(III) and As(V) were also determined in aqueous extracts. Total arsenic in the samples was determined by microwave digestion and inductively coupled plasma mass spectrometry (ICPMS). For arsenic speciation, a water extraction especially suitable for arsenosugars was used, and the arsenic species were analyzed by liquid chromatography with both anionic and cationic exchange and ICPMS detection (LC-ICPMS). The total arsenic content of the alga samples ranged from 5.8 to 56.8 mg As kg(-1). The mass budgets obtained in the extracts (column recovery × extraction efficiency) ranged from 38 to 92% except for U. pinnatifida (4%). The following compounds were detected in the extracts: arsenite (As(III)), arsenate (As(V)), methylarsonate (MA), dimethylarsinate (DMA), sulfonate sugar (SO(3)-sug), phosphate sugar (PO(4)-sug), arsenobetaine (AB), and glycerol sugar (Gly-sug). The highest concentrations corresponded to the arsenosugars.

Measurement of arsenic compounds in littoral zone algae from the Western Mediterranean Sea. Occurrence of arsenobetaine

The determination of arsenic compounds in algae collected on the Catalan coast (Western Mediterranean) is reported. Ten algae species and the seagrass Posidonia oceanica were analyzed. Total arsenic in the samples was determined by microwave digestion and inductively coupled plasma mass spectrometry (ICPMS). Arsenic speciation in water extracts of samples was analyzed by liquid chromatography with both anionic and cationic exchange with ICPMS detection (LC-ICPMS). The total arsenic content of the algae samples ranged from 2.96 to 39.0mg As kg(-1). The following compounds were detected: arsenite (As(III)), arsenate (As(V)), methylarsonate (MA), dimethylarsinate (DMA), sulfonate sugar (SO3-sug), sulfate sugar (SO4-sug), phosphate sugar (PO4-sug), arsenobetaine (AB), arsenocholine (AC), trimethylarsine oxide (TMAO) and glycerol sugar (Gly-sug). The main arsenic species found were arsenosugars. Significant percentages of arsenobetaine (0.54 mg As kg(-1), 28% of the extractable arsenic and 0.39 mg As kg(-1), 18% of the extractable arsenic) were found in Ulva rigida and Enteromorpha compressa. These results are discussed in relation to the presence of epiphytes.