Preparation and characterization of a new reference material for the inorganic analysis of corn flour.

Abstract

Corn is one of the most consumed cereals in world and the second most cultivated in Brazil. Cereal flour has a flavor well accepted by the Brazilian population. This work describes the preparation and characterization of a new corn flour reference material which can be used as a quality assurance tool to demonstrate the reliability of the analytical results obtained from inorganic analysis of cereals and their derivatives. The studied elements were Ca, K, Mg, P, Cu, Fe, Mn and Zn. Homogeneity and stability tests, material characterization and attribution of uncertainty value were performed in this work by following recommendations of ISO Guides 30–35. The material was shown to be homogeneous and stable for 15 months at temperatures of -10 C, ?25 C and ?45 C, with small uncertainty. Alternatively, the data were analyzed by hierarchical clustering technique and the stability was confirmed. The confidence ellipse technique enabled a simple and fast evaluation of data supplied by collaborating laboratories allowing the exclusion of outlying values and indicating possible causes of the deviations.