| Resumo: | Chemical speciation in foodstuffs is of uttermost importance since it is nowadays recognized that both toxicity and bioavailability of an element depend on the chemical form in which the element is present. Regarding arsenic, inorganic species are classified as carcinogenic while organic arsenic, such as arsenobetaine (AsB) or arsenocholine (AsC), is considered less toxic or even non-toxic. Fish samples, from 3 different species (gilthead sea bream, meagre and salmon), were subjected to three different cooking methods: boiling, grilling and roasting. Arsenic content was determined on both raw and cooked samples by Inductively Coupled Plasma Mass Spectrometry (ICP-MS). Speciation studies were carried out by coupling a High Performance Liquid Chromatographer (HPLC) to an ICP-MS. To guaranty the quality of results samples were analyzed in duplicates and a reference material was used for total concentration determination and for speciation studies complying with metrological requirements. The obtained results for total arsenic were between 265 µg.kg-1 and 7585 µg.kg-1. The lowest value was observed in the samples from boiled meagre and the highest in grilled gilthead sea bream. The speciation studies revealed that, even though fish samples presented a high content of arsenic, more than 90% of the arsenic present was in the form of arsenobetaine. Apparently, the culinary treatment does not enhance the interconversion of species.
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