A New Candidate Reference Material for Inorganic Arsenic and Arsenosugars in Hijiki Seaweed: First Results from an Interlaboratory Study

Narukawa, Tomohiro; Raber, Georg; Itoh, Nobuyasu; Inagaki, Kenji

doi:10.2116/analsci.19p306

Cited by 8 publications

(8 citation statements)

References 32 publications

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“…For NMIJ 7405b, the recoveries were acceptable for all the arsenicals, i.e., As 5+ (109%), DMA (125%), As-328 (116%), As-392 (99%), As-408 (104%), and As-482 (124%) (see Tables and ). Water was used as an extractant in certifying this material . The authors could not find literature data for either of the reference materials to compare the results of the other arsenic species.…”

Section: Resultsmentioning

confidence: 99%

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Arsenic Species in Seaweeds Commercially Available in the United States

Wolle

Todorov

Conklin

2021

ACS Food Sci. Technol.

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Arsenic was speciated in 46 seaweed samples purchased from the U.S. market, i.e., brown (arame, hijiki, kombu, knotted wrack, oarweed, wakame), green (sea lettuce), and red (dulse, Irish moss, laver, nori) macroalgae. The total arsenic (tAs) concentrations varied from 3000 to 105 000 ng/g (dry weight). Speciation analysis based on the extraction of water-soluble and nonpolar arsenic showed that, among the variety of arsenicals identified, arsenosugars were dominant in most seaweeds. Inorganic arsenic (iAs) did not exceed 350 ng/g except for knotted wrack (1760 ng/g), oarweed (8900−16 000 ng/g), and hijiki (50 800− 56 900 ng/g). While arsenate (As 5+ ) was the predominant form of iAs, arsenite (As 3+ ) was also detected in some samples such as oarweed and hijiki. Nonpolar arsenic accounted for 2−59% of the tAs; the highest percentages were in sea lettuce and wakame. Unknown arsenic species were found representing 0.1−12% of the tAs in the seaweeds. Reference materials and spike recovery tests were used for quality control. While the regulations are not applicable to products in the U.S., the iAs concentrations in the seaweeds (except hijiki and oarweed) are lower than the guidance levels established by several countries.

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Section: Resultsmentioning

confidence: 99%

“…Water was used as an extractant in certifying this material. 64 The authors could not find literature data for either of the reference materials to compare the results of the other arsenic species.…”

Section: Analysis Of Reference Materialsmentioning

confidence: 99%

Arsenic Species in Seaweeds Commercially Available in the United States

Wolle

Todorov

Conklin

2021

ACS Food Sci. Technol.

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“…We also used the same two procedures with CRM 7405-a (Hijiki) and obtained no significant differences (p > 0.05 in one-way ANOVA), although we observed a tendency towards slightly lower (ca 5-10%) arsenolipid recoveries when we employed the pyridine extraction method. Nevertheless, extraction with pure pyridine provides several advantages compared to alkaline CHCl 3 /EtOH: first, it obviates the need for alcohols during extraction and reduces the risk of chemical reaction; second, it avoids chlorinated solvents which often cause interferences during ICPMS determinations because of 35 Cl 40 Ar polyatomic interference on 75 As; and third, the pyridine extraction method extracts less water-soluble arsenicals. For these reasons, we decided to use the pyridine extraction method when possible.…”

Section: Extraction Of Arsenic Species From Collected Field Samplesmentioning

confidence: 99%

“…Anion-exchange HPLC-separations of Picocystis strain ML extracts were performed after Glabonjat et al [19] using a PRP-X100 column (4.6 × 150 mm; 5 µm particles) under isocratic conditions with 5 mM malonic acid (adjusted to pH 5.8 with NH 3 ) at a flow of 1.0 mL/min; temperature was 30 • C (injection volumes were 20 µL). Field-collected samples were chromatographed on a Thermo AS14A Dionex IonPac column (3.0 × 150 mm, 5 µm particles) under isocratic elution conditions adapted from Narukawa et al [35] using aqueous 10 mM formic acid (adjusted to pH 4.0 with NH 3 ) as mobile phase; flow was 0.7 mL/min; temperature was 30 • C (injection volumes were 5 µL). The outflow of the HPLC-system ran directly into the ICPMS (Agilent 7500ce or 7900).…”

Section: Determination Of Water-soluble Arsenicalsmentioning

confidence: 99%

Arsenolipids in Cultured Picocystis Strain ML and Their Occurrence in Biota and Sediment from Mono Lake, California

Glabonjat

Blum

Miller

et al. 2020

Life

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Primary production in Mono Lake, a hypersaline soda lake rich in dissolved inorganic arsenic, is dominated by Picocystis strain ML. We set out to determine if this photoautotrophic picoplankter could metabolize inorganic arsenic and in doing so form unusual arsenolipids (e.g., arsenic bound to 2-O-methyl ribosides) as reported in other saline ecosystems and by halophilic algae. We cultivated Picocystis strain ML on a seawater-based medium with either low (37 µM) or high (1000 µM) phosphate in the presence of arsenite (400 µM), arsenate (800 µM), or without arsenic additions (ca 0.025 µM). Cultivars formed a variety of organoarsenic compounds, including a phytyl 2-O-methyl arsenosugar, depending upon the cultivation conditions and arsenic exposure. When the cells were grown at low P, the organoarsenicals they produced when exposed to both arsenite and arsenate were primarily arsenolipids (~88%) with only a modest content of water-soluble organoarsenic compounds (e.g., arsenosugars). When grown at high P, sequestration shifted to primarily water-soluble, simple methylated arsenicals such as dimethylarsinate; arsenolipids still constituted ~32% of organoarsenic incorporated into cells exposed to arsenate but < 1% when exposed to arsenite. Curiously, Picocystis strain ML grown at low P and exposed to arsenate sequestered huge amounts of arsenic into the cells accounting for 13.3% of the dry biomass; cells grown at low P and arsenite exposure sequestered much lower amounts, equivalent to 0.35% of dry biomass. Extraction of a resistant phase with trifluoroacetate recovered most of the sequestered arsenic in the form of arsenate. Uptake of arsenate into low P-cultivated cells was confirmed by X-ray fluorescence, while XANES/EXAFS spectra indicated the sequestered arsenic was retained as an inorganic iron precipitate, similar to scorodite, rather than as an As-containing macromolecule. Samples from Mono Lake demonstrated the presence of a wide variety of organoarsenic compounds, including arsenosugar phospholipids, most prevalent in zooplankton (Artemia) and phytoplankton samples, with much lower amounts detected in the bottom sediments. These observations suggest a trophic transfer of organoarsenicals from the phytoplankton (Picocystis) to the zooplankton (Artemia) community, with efficient bacterial mineralization of any lysis-released organoarsenicals back to inorganic oxyanions before they sink to the sediments.

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“…The first results from an inter-laboratory comparison covering the certification of a new CRM, a Hijiki seaweed which will be certified for various As compounds including arsenosugars, has been published. 19 Water-soluble As compounds were extracted from dried, ground Hijiki either by agitation overnight at room temperature, or for 1 hour with UAE or with a solution of 0.01% w/v pepsin in 0.07 mol L −1 and heating at 37 °C for 2 hours. In each case the extracts were then centrifuged and filtered before analysis.…”

Section: Crms and Metrologymentioning

confidence: 99%