Off-line coupling of high-performance liquid chromatography and 1H nuclear magnetic resonance for the identification of filbertone in hazelnut oil

Abstract

A new procedure is presented for off-line coupling of high-performance liquid chromatography and proton nuclear magnetic resonance spectroscopy (1H NMR) in hazelnut oil analysis. The optimization of some parameters affecting both the liquid chromatography preseparation step and the effective multiple-solvent suppression required for the NMR study enabled us to determine the presence in a hazelnut oil of (E)-5-methyl-hept-2-en-4-one (filbertone), a marker previously proposed to detect the adulteration of olive oil with hazelnut oil. The described procedure requires the filtration of the oil prior to its introduction into the chromatographic system and combines the advantages of providing sufficient sensitivity and selectivity with simple methodology and reduced sample handling.