Inorganic and organic arsenic in some commercial east australian crustacea

The levels of inorganic and organic arsenic have been determined in a total of 86 samples of crustacea which included School prawns (Metapenaeus macleayi), King prawns (Penaeus plebejus), Royal Red prawns (Hymenopenaeus sibogae), Eastern Common crayfish (Jasus verreauxii), Blue Swimmer crab (Portunus pelagicus) and Mud crab (Scylla serrata). Most samples were obtained from New South Wales coastal waters and the remainder were purchased at the Sydney fish markets. Inorganic arsenic was isolated by distillation as the chloride and determined by an atomic absorption‐hydride generation method. Organic arsenic was determined on the remaining solution by flame atomic absorption spectrophotometry after digestion of the organic matter with a mixture of nitric, perchloric and sulphuric acids (25 + 5 +1). The Eastern Common crayfish contained the highest levels of inorganic and organic arsenic with ranges of 0.12–0.41 mg kg−1 and 11.9–54.1 mg kg−1 (wet basis), respectively. Of the remaining samples, 85% contained inorganic arsenic at <0.1 mg kg−1 and 97% contained organic arsenic at <7 mg kg−1. The absolute sensitivity and detection limit of the inorganic arsenic method was estimated to be 3 ng (0.03 mg kg−1). For the organic arsenic method the sensitivity and detection limits were estimated as 0.5 and 0.8 mg kg−1, respectively.