Determination of Total Inorganic Arsenic in Fish, Shellfish and Fish Products

Overview

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.

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.