Direct olive oil analysis by low-temperature plasma (LTP) ambient ionization mass spectrometry

A fast, reagentless, and direct method is presented for the mass spectrometric analysis of olive oil without any sample pretreatment whatsoever. An ambient ionization technique, the low-temperature plasma (LTP) probe, based on dielectric barrier discharge, is used to detect both minor and trace components (free fatty acids, phenolics and volatiles) in raw untreated olive oil. The method allows the measurement of free fatty acids (the main quality control parameter used to grade olive oil according to quality classes), selected bioactive phenolic compounds, and volatiles. The advantages and limitations of the direct analysis of extremely complex mixtures by the ambient ionization/tandem mass spectrometry combination are discussed and illustrated. The data presage the possible large-scale application of direct mass spectrometric analysis methods in the characterization of olive oil and other foodstuffs.