Zhao et al. 2014 - edible-seaweed arsenic digestion speciation

Zhao and colleagues measured total arsenic and four extractable arsenic species in five edible seaweeds purchased from Qingdao supermarkets. The paper separates water-extract, simulated-gastric, and simulated-intestinal arsenic species, so As(III), As(V), DMA, and MMA are recorded separately below. The source is directly relevant to seaweed/kelp foods, especially because the high total arsenic in Hizikia fusiformis is paired with high water-extract As(V) but lower simulated-gastric As(III).

Key numbers

Table 3 reports total arsenic in seaweed as mg/kg, dry weight, mean ± SD with n = 3:

Table 4 reports arsenic species in water, gastric, and intestinal extracts as mg/kg, dry weight, calculations based on arsenic contents, mean ± SD with n = 3:

Source-stated interpretation and risk-context values:

• The authors state that Hizikia fusiformis water-extract As(V) occupied about 27.9% of total As in the study.
• They state that As(V) and MMA were not detected in any gastric or intestinal extract, including Hizikia fusiformis.
• The simulated-digestion risk calculation used an adult body weight of 60 kg, a hijiki seaweed amount of 25 g, and the maximum gastrointestinal inorganic-arsenic concentration of 1.47 mg/kg, yielding inorganic arsenic intake of 0.6 µg/kg bw per day.

Quality-control and calibration values:

• CRM GBW 08517 Kelp: measured 13.2 ± 1.8 mg/kg; certified 13.9 ± 2.4 mg/kg.
• CRM GBW 08521 Laver: measured 40.2 ± 2.5 mg/kg; certified 41 ± 3 mg/kg.
• HPLC retention times were 3.07 min for DMA, 3.76 min for As(III), 6.60 min for MMA, and 9.00 min for As(V).
• Calibration curves covered 1 to 100 ng/mL; correlation coefficients were higher than 0.998; relative standard deviations for calibration points were 3.2% to 7.8% for 1 and 5 ng/mL and 0.8% to 4.5% from 10 to 100 ng/mL.

Methods (brief)

Five edible seaweeds were randomly purchased from Qingdao supermarkets during August and October 2012, oven-dried at 60°C to constant weight, ground, and homogenized. Total arsenic used 0.5 g dry weight portions digested with 5 mL concentrated nitric acid and 2 mL hydrogen peroxide in a microwave-assisted digestion system, followed by ICP-MS. Water-extract speciation used 0.5 g dried seaweed, 38 mL deionized water, ultrasonic extraction for 40 min, 2 mL of 3% (v/v) acetic acid for protein removal, centrifugation at 8000 ×g, 4°C, and 0.45 µm filtration before HPLC-ICP-MS. In vitro digestion used 1.0 g seaweed powder with saliva, gastric juice, duodenal solution, and bile at 37°C, simulating 5 min mouth, 2 h stomach, and 7 h intestine residence times; arsenic species were identified by matching HPLC retention times to standards.

Implications

This source contributes seaweed/kelp food occurrence evidence for both total arsenic and extractable inorganic arsenic species. It is especially useful for keeping Hizikia fusiformis water-extract As(V) (23.0 ± 2.5 mg/kg) separate from the simulated-gastric As(III) value (1.47 ± 0.20 mg/kg) and from total arsenic (82.5 ± 3.6 mg/kg). Downstream extraction should preserve the extract basis and should not use total As, DMA, or MMA as inorganic-arsenic substitutes.

Wiki pages this source may touch

• seaweed-kelp-foods
• seaweed
• arsenic-total
• arsenic-inorganic

Verification notes

• Identity checks before writing found no existing source page for DOI 10.1155/2014/436347, article ID 436347, raw handle MFK_zhao2014, title text, author/title text, or cite key zhao2014-edible-seaweed-arsenic-digestion.
• Text was extracted to /tmp/hmi-seaweed-068.txt with pdftotext -layout; title/authorship, sample collection, methods, Table 3, Table 4, QA/QC, calibration, and risk-assessment text were readable.
• All Key numbers were checked against /tmp/hmi-seaweed-068.txt, especially Table 3 total-As values, every Table 4 water/gastric/intestinal extract species value, CRM values, HPLC retention times, calibration/RSD values, the 27.9% Hizikia fusiformis statement, and the 60 kg/25 g/1.47 mg/kg/0.6 µg/kg bw per day risk-context calculation.
• Units and bases are preserved as mg/kg, dry weight, mg/kg, ng/mL, %, min, h, g, mL, µm, µg/kg bw per day, and °C; no unit conversion was performed.
• Speciation check: total As, As(III), As(V), DMA, and MMA are kept distinct. As(III) and As(V) are treated as inorganic arsenic context; DMA and MMA are not promoted to iAs.
• Brand firewall: samples are supermarket-purchased seaweeds by species, with no product brand names reported.
• Missing-slug check: no missing product or ingredient slug blockers. Exact seaweed species remain in Key numbers while frontmatter routes broadly to seaweed/kelp foods.

Page history

The five most recent substantive edits to this page. The full version history lives in git; when DOI minting comes online (see schema docs), each entry below will also link to a version-pinned DataCite DOI.