Saudi Arabian crude oil is a super complex mixture and, up to now, there has been little research into its heteroatom-containing compounds.First, oxygenated compounds (OCs) were isolated from Saudi Arabian oil using a Pd nanoparticle exchange complex, which formed between the nano-Pds and the oxygenated ligands.Normally, polycyclic aromatic sulphur heterocycles (S-PAHs) are separated from petroleum oil via the same method.The obtained results reveal that all the OC formulations with S-PAHs can be separated from the pre-isolated aromatic fraction of crude oil via this approach.S-PAHs are mixtures of benzothiophene and dibenzothiophene congeners.The isolated OCs are composed mainly of hydroxyl compounds.The liquid chromatography (LC)/electrospray ionization (ESI) in positive ion mode ESI (+)/tandem mass spectrometry (MS/MS) technique was used to assign the molecular weight distribution and identify the isolated OCs.The LC/ESI (+)-MS/MS technique differentiates S-PAHs and OCs using protonated ions.Thus, LC/ESI (+)-MS/MS can be used to assign molecular weight distributions for both the groups as a single mixture.MS/MS in precursor ion mode was used for the immediate identification of the target S or O analytes.