Electrospray mass spectrometric determination of 1-nitropyrene and non-substituted polycyclic aromatic hydrocarbons using tropylium cation as a post-column HPLC reagent

A method is presented for the electrospray mass spectrometric determination of 1-nitropyrene and non-substituted polycyclic aromatic hydrocarbons (PAHs) using tropylium cation as a post-column HPLC reagent. In the method, the analytes form a pi-pi complex with the tropylium cation by mixing with the tropylium solution after the separation of 1-nitropyrene and PAHs by reversed-phase liquid chromatography. The complexes then transfer the cations of the polycyclic aromatic compounds (PACs) and the tropylium compounds by collision-induced dissociation (CID) at the ion transfer region of the electrospray system. The generated PAC cations are detected by mass spectrometry. With the proposed method, 1-nitropyrene and PAHs could be simultaneously determined, and the detection limits (S/N=3) in the selected-ion monitoring mode were 0.83 ng of the injected 1-nitropyrene and 0.67-1.24 ng of PAHs.