CLOSED-VESSEL MICROWAVE ACID DIGESTION OF FOODSTUFFS AND TRACE ALUMINUM DETERMINATION BY GRAPHITE-FURNACE ATOMIC-ABSORPTION SPECTROMETRY

The estimation of the daily dietary intake of aluminum is part of an o ngoing project aimed at the assessment of the daily intake of food con stituents by the Belgian population. This requires a reliable analytic al method that is applicable to different solid foodstuffs and can eas ily be implemented in an analytical laboratory. A method is proposed f or the dissolution of food samples with microwave digestion (HNO3-H2O2 2:0.5) and for the subsequent Al determination by graphite furnace at omic absorption spectrometry. The use of closed-vessel microwave acid digestion shortens the time for sample dissolution and improves the an alysis quality. A direct calibration against aqueous solutions was use d for all of the foodstuff digests. For the method validation, standar d reference materials were analyzed. Aluminum was determined in 13 dif ferent types of bread and 30 types of fish. The limit of detection in solution is about 3 mu g/L (3 sigma). Some samples with relatively hig her aluminum content were identified.