Empleo de las técnicas atómicas para el análisis multielemental y la especiación en alimentos.

Abstract

The main contribution of this thesis has been the study, development and comparison of analytical procedures, for the determination of the total content of metals and metalloids by ICP-MS in commercial milk and the extraction of As, Sb, Se, Te, Bi and Hg chemical species in two groups of food: milk and fishing products, using HG-AFS and CV-AFS. Different analyses protocols have been developed in order to guarantee the quality and food safety in basic food, such as milk and the content of toxic species of As and Hg in fish. In the design of protocols we have always searched to minimize the previous treatment of the sample, the use of the least dangerous reagents and the minimal generation of residues. For the analysis of milk there was designed a microwave-assisted digestion using mixtures of nitric acid and hydrogen peroxide, procedure that was adapted for the later analysis by HG-AFS. As an alternative to the total digestion of samples, a procedure based on the ultrasound-assisted extraction at room temperature by using different acids was developed. The previous procedures were applied to the determination of 45 elements in milk by ICP-MS successfully. Likewise, the acid leaching allowed the speciation of As, Sb, Se and Te into their oxidation states in milk by means of the use of non-chromatographic procedures, and the speciation of As and Hg in fish. Finally, all these protocols have been validated through recovery studies, comparison with reference methods and / or analysis of certified samples, and they have been determined their analytical characteristics: limits of detection, sensibility, precision and accuracy, which are suitable for the quality control in milk and fishing products.