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Determination of inorganic arsenic species in food by in situ irridium trapping ETAAS method

Information on the chemical form in which arsenic is present in food is of great importance in the assessment of food safety. Toxicity is generally associated with the inorganic forms of arsenic: arsenite (As3+) and arsenate (As5+) which may be present in food in a proportion from 1 % to 3 % of the total arsenic content. Of particular interest are arsenic species in rice and rice-based products due to high concentration inorganic arsenic the potential exposure of specific population [1]. The analytical methodology for the quantification of arsenic species is generally based on the combined systems of high performance liquid chromatography (HPLC) with atomic fluorescence spectrometry (AFS) or inductively coupled plasma mass spectrometry (ICP-MS) [2, 3]. The analytical approach and the method selection are primarily determined by available technology, the composition of the matrix and the moieties of arsenic present in the sample. In this work the hydride generation ETAAS with in situ trapping on an iridium-coated graphite tube was used for inorganic species analysis in variety of food. Sample preparation was denaturation and solubilization of the protein matrix in concentrated hydrochloric acid which allowed release of all arsenic species into solution and the subsequent extraction of the inorganic arsenic present in the acidic media using chloroform. The method is robust and applicable for various food samples with the inorganic arsenic amount of 0.01 mg kg-1 to 7.5 mg kg-1. We measured the concentration range of inorganic arsenic in different categories of food: rice and rice products (0.060 - 0.196) mg kg-1 ; cereal based foods for infants and young children containing rice (0.017 - 0.119) mg kg-1 ; sea fish (sardines, tuna and mackerel) (0.010 - 0.070) mg kg-1 ; grains (0.010 - 0.016) mg kg-1 and fresh vegetables (0.010 - 0.013) mg kg-1. The accuracy and precision of the method was evaluated by using different certified reference materials: NIST 1568 b Rice Flour (R = 93 %), ERM CE278k Mussel tissue (R = 114 %) and IAEA 359 Cabbage (R = 92 %).

inorganic arsenic ; hydride generation ; ETAAS ; iridium-coated graphite tube

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