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

Overview

Lorenc and colleagues developed and validated a combined HPLC/ICP-MS and UPLC/ESI-MS/MS workflow for arsenic in algae products. The occurrence-relevant data are the total arsenic and arsenic-speciation values in Table 2 for five algae/seaweed materials, including a commercial cooked/dried hijiki product, nori sheets, serrated wrack, and two reference materials. Unknown arsenic and arsenosugar species are kept separate from inorganic arsenic.

Key numbers

Table 2 reports total arsenic before extraction as mg kg-1 (c ± SD) and extracted/speciated arsenic as mg kg-1 (c ± U, k = 2). No unit conversion was performed.

The abstract summarizes edible algae tAs as (19.28 ± 0.45) mg kg-1 to (72.6 ± 2.7) mg kg-1, As(III) as <LOD to (8.97 ± 0.59) mg kg-1, As(V) as <LOD to (5.95 ± 0.29) mg kg-1, DMA as <LOD to (0.766 ± 0.040) mg kg-1, and unknown arsenic species as 28% to 100% of extracted tAs.

Reference-material checks and method figures:

• NMIJ CRM 7405-a Hijiki tAs was (34.38 ± 0.99) mg kg-1 versus certified (35.8 ± 0.9) mg kg-1.
• NIST SRM 3232 Kelp Powder tAs was (45.4 ± 1.4) mg kg-1 versus certified (38.3 ± 1.34) mg kg-1; the source states this was not in as good accordance as the NMIJ CRM.
• The source reports LODs of 0.041 mg kg-1 for tAs, 0.12 mg kg-1 for extracted tAs, 0.55 mg kg-1 for AsB, 0.61 mg kg-1 for As(III), 0.57 mg kg-1 for DMA, 0.64 mg kg-1 for MMA, and 0.55 mg kg-1 for As(V).
• MMA was not detected in any sample. AsB was detected only in one Fucus serratus extract.

UPLC-HRMS identification context from Table 4 includes DMA(V), arsenate(V), MMMTA(V), MTA(V), DMAE, DMDTA(V), MMDTA(V), DMAA, pentylarsonic acid, dimethylarsinoylribose, multiple methylated arsenosugars, and one unknown arsenic compound. The authors report a high variety of As-sugars (12 compounds) and eight additional simple organic arsenic compounds; these organoarsenic identifications are not collapsed into inorganic arsenic.

Methods (brief)

The study analyzed five seaweed materials: NMIJ CRM 7405-a Hijiki, a cooked/dried Sargassum fusiforme hijiki product, Pyropia yezoensis nori sheets for sushi, Fucus serratus serrated wrack, and NIST SRM 3232 Kelp Powder. Nori and hijiki were ground before digestion/extraction; NMIJ CRM, NIST SRM, and serrated wrack were not further ground. Total arsenic used microwave-assisted digestion with nitric acid and hydrogen peroxide at 200 °C, followed by ICP-DRC-MS monitoring 91AsO+ with 73Ge+ internal standard.

Speciation used ultrasound-assisted extraction (UAE) and microwave-assisted extraction (MAE) with water or water:methanol (1:1, v/v) after nitric-acid extraction was discarded because it changed As speciation. For each extraction, 200 mg algae material was extracted with 20 mL extracting agent for 30 min; MAE was at 60 °C and UAE at room temperature. HPLC/ICP-DRC-MS used a Hamilton PRP-X100 anion-exchange column. UPLC/ESI-MS/MS was used for unknown arsenic-species identification.

Implications

This source provides a method-centered but routeable arsenic-speciation dataset for algae/seaweed products. It supports seaweed/kelp food and algae/seaweed supplement context with total arsenic and source-measured As(III), As(V), DMA, and unknown-organoarsenic fractions. Because the source’s conclusion emphasizes arsenosugars and other unknown organoarsenic species, downstream extraction must preserve speciation and must not treat total arsenic or arsenosugars as inorganic arsenic.

Wiki pages this source may touch

• Seaweed/kelp foods (nori, wakame, kombu, dulse — as food products)
• Ingredient class — algae/seaweed-based
• Seaweed
• Arsenic, Total
• Arsenic, Inorganic

Verification notes

• Identity checks before writing found no existing source page for DOI 10.1016/j.talanta.2020.121384, raw handle MFK_lorenc2020, title text, or cite key lorenc2020-marine-algae-arsenic-species.
• All Key numbers were rechecked against /tmp/hmi-seaweed-043.txt, extracted with pdftotext -layout. Table 2 was transcribed as available in the extracted text; NIST SRM 3232 appears with two UAE rows in the text layer, while the prose states its MAE signals were broad and could not be assigned to specific compounds.
• Units and bases are preserved as mg kg-1, %, mg, mL, min, and °C; no unit conversion was performed.
• Speciation check: As(III), As(V), DMA, AsB, MMA, unknown arsenic, and arsenosugar/organic species remain separate. No tAs value or arsenosugar identification is promoted to iAs.
• Brand firewall: the source does not name consumer brands; the page records product forms/material types and CRM/SRM identities only.
• Missing-slug check: no missing product or ingredient slug blockers. Exact nori, hijiki, serrated wrack, Fucus, and kelp powder terms remain in source text while frontmatter uses broad seaweed/kelp and algae/seaweed supplement slugs.

Update history

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