HPLC retention behavior of poly-aromatic-hydrocarbons on aminopropyl silica gels modified with Cu(II)- and Ni(II)-phthalocyanine derivatives in non-polar eluent

A comparative study was conducted to elucidate the mechanism underlying the separation of poly-aromatic-hydrocarbons (PAHs) and related compounds thereof on a column packed with silica gels modified with Ni(II)- or Cu(II)-phthalocyanine derivatives (PCS) (Ni- or Cu-PCS_D column) and commercially available PYE® and NPE® columns with a non-polar eluent, such as n-hexane. It has been revealed that the dominant interaction responsible to the separation of PAHs on the Cu-PCS_D and the PYE® columns with n-hexane is the π-π interaction; however, in the separation of PAHs having 4 rings such as pyrene on the Ni-PCS_D column, participation of π-d interaction was indicated. The predominant role of π-π interaction in the separation of PAHs of less than three rings on the Ni-PCS_D column was demonstrated using anthracene. All the columns possessed planar recognition ability and were estimated to be potentially useful in the separation and the analysis of PAHs.