Overview
García Salgado et al. developed a microwave-assisted water extraction and HPLC-HG-ICP-AES method for soluble arsenic species in algae. The paper analyzes Sargassum CRM material, Chlorella vulgaris, market Hizikia fusiformis dry material, and market Laminaria digitata capsules. Total arsenic, inorganic arsenic species, and methylated arsenic species are kept separate below.
Key numbers
The paper reports total arsenic in the four algae/materials as µg g−1 arsenic, dry-weight context:
| Sample/material | Total arsenic |
|---|---|
| NIES No. 9 Sargassum CRM | 106 ± 6 µg g−1 |
| Hizikia fusiformis | 88 ± 6 µg g−1 |
| Laminaria digitata | 41 ± 4 µg g−1 |
| Chlorella vulgaris | 39 ± 3 µg g−1 |
Table 3 compares extraction efficiencies for three consecutive 8 mL deionized-water extraction steps:
| Sample/material | Ultrasonic focused probe (20 kHz, 30 s) | Microwave oven (90°C, 5 min) |
|---|---|---|
| NIES No. 9 Sargassum CRM | 65 ± 3% | 98 ± 5% |
| Hizikia fusiformis | 69 ± 4% | 88 ± 5% |
| Laminaria digitata | 67 ± 4% | 78 ± 4% |
| Chlorella vulgaris | 64 ± 3% | 85 ± 5% |
Table 5 reports quantitative arsenic species in µg g−1 arsenic (mean ± standard deviation, n = 3) by HPLC-HG-ICP-AES:
| Sample/material | As(III) | As(V) | MMA | DMA | Total As extracted | Speciation recovery |
|---|---|---|---|---|---|---|
| NIES No. 9 Sargassum CRM | not detected | 72 ± 3 | not detected | not detected | 113 ± 5 | 64 ± 3% |
| Hizikia fusiformis | not detected | 62 ± 2 | not detected | not detected | 77 ± 3 | 80 ± 3% |
| Chlorella vulgaris | 6.1 ± 0.4 | 11.8 ± 0.5 | 2.2 ± 0.3 | 15 ± 2 | 33 ± 5 | 106 ± 9% |
For Laminaria digitata, none of the four target species was identified by HPLC-HG-ICP-AES. The paper reports an unknown arsenic species in the HPLC-ICP-AES chromatogram, eluting in the dead volume and estimated as 7.0 ± 1.1 µg g−1 arsenic.
Table 4 reports detection limits as absolute ng As: As(III) 0.5, DMA 2.0, MMA 1.0, and As(V) 2.0. Relative standard deviations were As(III) 3.3%, DMA 4.5%, MMA 3.7%, and As(V) 4.8%.
Table 6 spiked Hizikia stability recoveries were As(III) 95 ± 3%, DMA 92 ± 8%, MMA 115 ± 9%, and As(V) 93 ± 7%; for As(V), the source subtracts the 16.8 µg already present in the sample from the found concentration.
Methods (brief)
Approximately 200 mg of algae was extracted with 8 mL deionized water by microwave heating at 90°C for 5 min; the extraction was repeated three times, then extracts were centrifuged and filtered. Total arsenic was measured by ICP-AES after microwave digestion. Arsenic species studied were As(III), As(V), MMA, and DMA, separated on an anion-exchange Hamilton PRP-X100 column and detected by HPLC-HG-ICP-AES. Hydride generation used 4 M HCl, 0.5% (w/v) NaBH4, and 350 kPa carrier argon pressure.
Implications
The market Hizikia result is the most directly relevant food occurrence row in this paper: total arsenic 88 ± 6 µg g−1 with measured As(V) 62 ± 2 µg g−1 in the water extract. The Chlorella result is relevant to algae-based supplement context because it reports both inorganic and methylated soluble arsenic species. The Sargassum CRM is QA/context rather than a consumer product row, and the Laminaria capsule result should be treated cautiously because the target toxic species were not detected while an unidentified arsenic species was observed.
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 DOI, raw-handle, or cite-key page for
10.1016/j.chroma.2006.06.083,MFK_10-1016-j-chroma-2006-06-083, orgarcia-salgado2006-soluble-arsenic-algae. - All Key numbers were rechecked against
/tmp/hmi-seaweed-003.txt, extracted withpdftotext -layout, especially Tables 3, 4, 5, and 6 plus the total-arsenic values in the sample-description text. - Speciation check: Table 5 values are kept as As(III), As(V), MMA, and DMA. Total arsenic is not substituted for inorganic arsenic.
- Units are preserved as
µg g−1,%,ng As, andµg; no conversions were performed. - Evidence tier B reflects peer-reviewed method/speciation data with exact species and method validation, but a small sample set and inclusion of a CRM/research material rather than a full market survey.
- Brand firewall: no sampled brands are reported; market purchase is retained only at category level.
Update history
The five most recent substantive edits to this page, classified major (evidence or structure moved), correction (a published value or statement was wrong and has been fixed), or minor (narrative rewritten without changing the underlying evidence). Each description is derived from what the edit did to this page; the linked commit is the authoritative record, routine regeneration passes are excluded, and 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.