Fuente: WIPO "olive oil" Systems and methods are provided for selectively filtering 1,2-diolein and 1,3-dioleine ions from an olive oil sample. An ion source is instructed to ionize a mixture of an olive oil sample and a pre-ionization modifier. The pre-ionization modifier includes silver (Ag). A differential mobility spectrometry (DMS) device is instructed to separate ions received from the ion source and affected by a post- ionization modifier based on ion mobility. The second post-ionization modifier is butanol, for example. The DMS device is instructed to selectively filter separated 1,2-diolein precursor ions by selecting a first compensation voltage (CoV) for the DMS device. The first CoV is specific to separate 1,2-diolein precursor ions from 1,3-diolein precursor ions. The DMS device is instructed to selectively filter separated 1,3-diolein precursor ions by selecting a second CoV for the DMS device. The second CoV is specific to separate 1,3-diolein precursor ions from 1,2-diolein precursor ions.