Multi-elemental analysis of the samples was performed by Inductively Coupled Plasma Mass Spectrometry (ICP-MS). It is a particularly accurate technique, even at low concentrations (ppb, ppt) with high speed and high sensitivity measurements for all elements, providing the possibility to be used for qualitative and quantitative analysis.

The basic principle of the methodology is based on the generation of ions by the inductively coupled plasma and then the rapid separation and detection (based on the mass-to-charge ratio, m/z) of the ions by the mass spectrometer.

The analysis was performed by the ICP-MS system of Agilent (series 7850 ICP-MS) of the Plant Production laboratory of the Department of Food Science and Technology at University of Patras. This type of instrument includes a quadrupole mass spectrometer and an additional ORS (Octopole Reaction System) isobaric barrier removal system.