Determination of cobalt and manganese in food seasonings by flame atomic absorption spectrometry after preconcentration with 2-hydroxyacetophenone-functionalized polyurethane foam

The use of chelating reagents impregnated or incorporated into solid sorbents has been widely employed for the preconcentration of metal species. The determination of metal concentrations in foods is very important because the diet is the main route of intake for these elements. In this work, polyurethane foam (PUF) functionalized with 2-hydroxyacetophenone through a covalent group (–NC–) was applied as a preconcentration system for the determination of cobalt and manganese in food. PUF was reacted with 2-hydroxyacetophenone in a dioxane medium. The mixture was heated to 90 °C and held at reflux for 72 h with continuous stirring. The solid sorbent produced was used in a preconcentration system for the determination of Co and Mn. Chemical and flow variables affecting the preconcentration were studied. Under optimized conditions, the enrichment factors were 36-fold and 27-fold for cobalt and manganese, respectively. The limits of detection obtained for the solid sample analysis were 0.4 μg g−1 (Co) and 0.4 μg g−1 (Mn). The method was applied to the determination of cobalt and manganese in several common food seasonings.