Selective Determination of Inorganic Arsenic (III), (V) and Organic Arsenic in Biological Materials by Solvent Extraction- Atomic Absorption Spectrophotometry

Abstract

A new method for the selective determination of inorganic arsenic (III), (V) and organic arsenic has been performed. Each chemical form of arsenic in biological materials was solubilized in 6 n hydrochloric acid. Inorganic arsenic (III) was extracted into toluene from 9 n hydrochloric acid solution, and inorganic arsenic (V) was also extracted after reduction by potassium iodide. Organic arsenic was retained in hydrochloric acid solution. After arsenic in toluene solution was back-extracted into water, aqueous or hydrochloric acid solution containing arsenic was wet digested with a mixture of HNO₃, H₂S0₄ and HCIO₄, and arsenic was determined by atomic absorption spectrophotometry. The proposed method was applied to some kinds of algaes, shark muscle and orchard leaves (NBS SRM 1571). 90~ 100% of arsenic in algaes (Wakame, Arame, Kazime) and shark muscle was organic, while all the arsenic in orchard leaves was inorganic.