Control of olive oil adulteration with copper-chlorophyll derivatives

The present work proposes an analytical method able to detect in an adulterated olive oil sample the addition of the copper complexes of chlorophylls (E 141i). The method consists of a pigment extraction in liquid phase and subsequent analysis by HPLC-DAD. The profile of chlorophyll pigments of an olive oil is determined essentially by its content in pheophytins (a and b), but in no case any copper derivative. Different samples of colorant E 141i have been analyzed, the natural coloring additives used to adulterate vegetable oils. The 99.59 ± 0.52% of the chlorophyll pigments present in the different samples of E 141i colorant are not those of an olive oil (more than 75% are cuproderivatives). Thus, the simple detection of one of the compounds in an olive oil indicates adulteration. The major chlorophyll derivative in all the E 141i colorants samples is Cu-pyropheophytin a and its limit of detection (LOD) defined at a signal-to-noise ratio of about 3 was 6.58 ng/g. © 2009 American Chemical Society.We are sincerely grateful to the Comision Interministerial de Ciencia y Tecnología of the Spanish Government (CICYT) for supporting this research project, (AGL 2007-66139-C02-01/ALI) and to the Junta de Andalucía for supplementary financing.Peer Reviewe