DETERMINATION OF POTENTIALLY TOXIC AND ESSENTIAL ELEMENTS IN COUSCOUS FROM ARABIC COUNTRIES USING ICP-MS AND ICP-OES
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Couscous, which is made of semolina and flour, constitutes a primary food staple in many Arabic countries (such as Libya, Tunisia, Algeria, and Morocco), as well as the second most popular dish in France and other parts of the world. It is thus important to ensure its safety for consumption. This thesis looks at both potentially toxic (As, Se, Cd and Al) and essential elements (Cu, Zn, Fe, Mn, Mg, Mo, P, and S) in couscous, using an approach that can be used for realistic risk assessment. The analysis was carried out by inductively coupled plasma (ICP) optical emission spectrometry (OES) and mass spectrometry (MS), which were both used to assess the bio-accessibility of potentially toxic and essential elements in couscous. An ICP-MS instrument equipped with a collision-reaction interface (CRI) was used to mitigate the impact of polyatomic interferences. Closed vessel digestion was performed for the determination of total concentrations. A conventional batch method, involving artificial saliva, gastric juice and intestinal fluid as extracting agents, was used to provide a good approximation of the bioaccessibility of potentially toxic and essential elements in couscous. The results revealed that the majority of elements were released by gastric juice and then saliva. In contrast, no detectable amount of elements was released by artificial intestinal juice. Both the total and bio-accessible concentrations of elements, which are all at levels making couscous safe for consumption, vary greatly, likely depending on geographic location and perhaps on the several food processing steps.