Brooke 1981 - Fish and shellfish inorganic arsenic

Brooke and Evans developed two methods for determining total inorganic arsenic in fish, shellfish, and fish products. The paper is method-focused, but Table V reports occurrence-style values for total arsenic and inorganic arsenic in fish and shellfish sample rows. Inorganic arsenic is reported as the sum of the inorganic valency states isolated by the methods; total arsenic remains a separate tAs measurement.

Key numbers

The abstract states that the derived detection limit and confidence intervals were calculated for the distillation method. The Results and Discussion section gives a practical limit of detection of 0.02 mg kg-1; 95% confidence intervals of 0.02 mg kg-1 apply up to 0.10 mg kg-1, and above this the confidence interval is 20%.

Table V compares total arsenic with inorganic arsenic by procedures A and B in mg kg-1:

The conclusions state that total inorganic arsenic in the tested fish species did not exceed 0.10 mg kg-1, and that inorganic arsenic expressed as a percentage of total arsenic varied from less than 1 to 5%. This statement excludes the NBS orchard-leaves reference row and does not convert total arsenic into inorganic arsenic.

Methods (brief)

Procedure A isolated inorganic arsenic by distilling it from hydrochloric acid and measuring arsenic(III) after hydride generation by atomic-absorption spectrophotometry with atomisation in a flame-heated silica tube. The procedure weighed 5 g of representative wet fish sample or 2 g of dry sample, added iron(II) sulphate, refluxed with hydrochloric acid, and collected 50 ml of distillate. Procedure B dissolved sample in sodium hydroxide, chelated and solvent-extracted inorganic arsenic, back-extracted into nitric acid, oxidized, and measured arsenic(V) by the same hydride-generation AAS system.

Implications

This source provides historical fish and shellfish evidence for inorganic arsenic alongside total arsenic in the same sample rows. It is useful for speciation-aware seafood routing because total arsenic values in fish and shellfish were much higher than the inorganic arsenic values. Downstream use should preserve the paper’s mg kg-1 basis and treat the NBS dried tuna row as a reference-material result, not a retail product or brand finding.

Verification notes

• PDF text was extracted with pdftotext -layout; Table V and the Results and Discussion detection-limit sentence were checked against /tmp/ingest_f3_brooke1981.txt.
• DOI 10.1039/AN9810600514, raw handle MFK_brooke1981, and cite-key checks found no existing source page before creation.
• Table V values were copied exactly, including duplicate-pair formatting and the source’s <0.02 result for plaice by Procedure B. Units are preserved as mg kg-1; no conversion to wet weight, dry weight, ppm, or ppb was performed.
• Speciation: inorganic arsenic is source-reported total inorganic arsenic; total arsenic remains tAs. No total arsenic value is treated as inorganic arsenic.
• Brand firewall: no retail brand contamination values are reported. NBS dried tuna is a reference material row and is not treated as a brand.
• Frontmatter slugs were checked against docs/gpt-collaboration/taxonomy-snapshot.md; narrow species/product slugs for herring, haddock, whelks, lobster, prawns, and plaice are not in the closed product vocabulary, so broad seafood/fish/shellfish routing is used.

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.