Multielemental fractionation in pine nuts (Pinus pinea) from different geographic origins by size-exclusion chromatography with UV and inductively coupled plasma mass spectrometry detection

Abstract

Pine nuts (Pinus pinea) from different geographical origin in Spain and Portugal have been investigated concerning total element content and metal-biomolecules size distribution patterns Mn, Zn, Ni and Cu. All the studied metals were at the highest concentration in pine nuts from Faro and at the lowest from Catalu˜na. The most abundant element in samples was Mn at concentrations in the range of 26 g g−1 (Catalu˜na) to 559 g g−1 (Faro). Zn was also present at high concentration in samples, from 25 g g−1 (Catalu˜na) to 113 g g−1 (Faro). To a deeper insight to obtain classification rules for samples, pine nuts were analyzed by size-exclusion chromatography (SEC) with UV detection and inductively coupled plasma mass spectrometry (ICP-MS). Two columns were used covering the molecular weigh range from <10 to 70 kDa that allowed the discrimination of the studied samples. Data reveal that the most differential UV-profile with low molecular weight (LMW) column was obtained with pine nuts from Huelva. This column allows good discrimination in the range of 2126–1352 Da in which a lot of peaks can be used to differentiate samples. The UV profiles obtained with the high molecular weight (HMW) column allows a poorer differentiation of samples, but pine nuts from Huelva, Castilla and Madrid are clearly distinguished to the others. In relation to fractionation patterns of metals, Mn allows a good discrimination between samples (LMW column), Cu was the only one associated to fractions at MW> 70 kDa in sample from C´adiz, and profiles of Ni and Zn are clearly different in terms of abundance of peaks. All these chromatographic profiles for elements give valuable information about the geographical origin of the studied samples and the differences found are discussed in this work