Comparison of methods for inorganic trace element analysis in croatian olive oils

Abstract

The aim of the present study was a comparison of the analytical methods optimized for the determination of trace elements in olive oils as a basis for further investigations, such as adulteration detection or geographical characterization.Different types of sample preparation procedures prior to ICP-AES and GFAAS determinations were investigated: both open and closed vessel digestion in a steel bomb, as well as microwave-assisted digestion using a closed system, which was selected for further investigations. Recoveries for all elements in olive oil were > 95%. Good reproducibility (up to 10% RSD) was achieved for the measurements of the elements analysed. The sensitivity of the ICP-AES technique was sufficient for the determination of Ca, Fe, Mg and Zn (relative standard deviation approx. 2%). Furthermore, the proposed digestion method allowed the GFAAS determination of Al, Co, Cu, K and Ni in the concentration range of 0.1 to 1.5 μg/g, with relative standard deviations of approximately 3 to 10% for all samples.