OPTIMIZATION OF ANALYTICAL METHODS FOR ORIGIN ASSESSMENT OF ORANGE JUICES .2. ICP-MS DETERMINATION OF TRACE AND ULTRA-TRACE ELEMENTS

The optimum conditions for the determination of the elemental composit ion of orange juices by atomic absorption spectroscopy (AAS) and ICP-o ptical emission spectroscopy (OES) or mass spectrometry (MS) have been determined on two sets of fruits collected in Brazil and in Israel. T he ICP-MS technique was then applied to the study of 64 fruit juices p ertaining to six different countries (Argentina, Brazil, Israel, South -Africa, Morocco and Spain) and obtained from six orange varieties (Na vel, Navelinas, Navel Late, Valencia, Valencia Late and Salustiana). I n order to take into account differential effects resulting from varia tions in the dry matter concentration the elemental composition was no rmalized with respect to nearly invariant elements in the ppm (Mg) and ppb (Sc) range. Variance analysis was applied to the 44 elemental com positions determined by ICP-MS or ICP-OES in order to determine the mo st discriminating elements in terms of geographical origin and variety . A panel of elements was selected to constitute the best geographical indicators. This analysis improves the performances of molecular and stable isotope analysis for origin assessment.