Zinc and Manganese Analysis in Maize by Microwave Oven Digestion and Flame Atomic Absorption Spectrometry

A conventional microwave oven acid digestion system was tested for sample digestion prior to the analysis of zinc and manganese in maize. The digestion procedure was based on sample dissolution with nitric acid using microwave heating in closed vessels. Under the working conditions used, the reagents employed to attack the samples do not significantly alter the flame atomic absorption of zinc and manganese; nor is any interference from other metals at their typical concentrations in maize formulations observed. As a result, zinc and manganese can be determined by running a calibration curve from aqueous solution of the two elements. Maizes can be effectively dissolved by treatment with microwave oven in approximately 15 min for the rapid determination of zinc (18 μ gg-1) and manganese (3 μ gg-1) by flame atomic absorption spectrometry. The relative standard deviation of the results was typically c. 3%.