Sensitive determination of benzo(a)pyrene in vegetable oils based on the electrochemiluminescence quenching of ruthenium (II) dipyrido[3,2-a:2′,3′-c]phenazine complex

A sensitive method for the determination of cancerogen benzo(a)pyrene (BaP) was proposed based on the electrochemiluminescence (ECL) property of a ruthenium(II) complex, [Ru(bpy)2dppz]2+ (Ru-dppz). With the π-π interaction between the ligand of dppz and BaP, the metal to ligand charge transfer of Ru-dppz might be disturbed, which inhibits the ECL behavior of Ru-dppz. The orientations of the π-π interaction between Ru-dppz and BaP were calculated via DFT theory. The negative value of binding energy confirmed both of the parallel displaced stacking and T-shape stacking could occur but the more negative binding energy value of parallel displaced stacking confirmed the preferred orientation. The ECL quenching yield was utilized to determine BaP, the linear range and the detection limit of BaP were estimated as 50 nM-15 μM and 2.45 nM, respectively. The recoveries of BaP in several kinds of vegetable oils were in the range of 97%∼108%, indicating the detection of BaP in fresh oils was reliable. However, the recovery of BaP in deep fried colza oil appears some deviation compared with which achieved by GC–MS, indicates the selectivity for the detection of PAHs depends on the ECL quenching of ruthenium complexes via π-π stacking still has the potential to be improved by optimizing the conjungation system of the ligands.