Direct analysis of olive oil and other vegetable oils by mass spectrometry: a review

Abstract Virgin olive oil (VOO) is a highly valued vegetable oil often subjected to fraud practices such as adulteration with lower prized oils such as seed oils and refined olive oil. Thus, there is a need to provide rapid tools that allow high-throughput authentication and quality control of VOO as well as other valued oils. Mass spectrometry offers unique features -such as specificity, sensitivity and speed of analysis-that map well against this challenge, either those based on atmospheric pressure ionization methods (ESI and APCI) or those occurring under vacuum conditions such as MALDI for nonvolatile species or headspace sampling-mass spectrometry using electron impact ionization (HS-MS) or chemical ionization (proton transfer reaction mass spectrometry (PTR-MS) and selected ion flow tube mass spectrometry (SIFT-MS)) for volatile fraction analysis. In addition, more recent atmospheric pressure methods (Ambient MS) enable direct analysis with minor or even no sample manipulation. The aim of this article is to provide a critical overview on all these methods and their potential use for vegetable oil characterization, highlighting the strengths and weaknesses of the different approaches.