Laser-excited time-resolved Shpol'skii spectroscopy for the direct analysis of dibenzopyrene isomers in liquid chromatography fractions

We present a unique method for the unambiguous determination of dibenzo[a,l]pyrene, dibenzo[a,e]pyrene, dibenzo[a,e]pyrene, dibenzo[a,h]pyrene, and dibenzo[e,l]pyrene in high-performance liquid chromatography (HPLC) fractions. Chemical analysis is performed via laser-excited time-resolved Shpol'skii spectroscopy with the aid of a cryogenic fiber-optic probe, pulsed tunable dye laser, spectrograph, and intensified charge-coupled device. Unambiguous identification is accomplished via wavelength time matrix formats, which give simultaneous access to spectral and lifetime information. Prior to spectroscopic analysis, HPLC fractions are pre-treated with liquid-liquid extraction or solid-liquid extraction at the tip of the fiber-optic probe. Solid-liquid extraction gives the best limits of detection, which vary from 40 pg mL(-1) (dibenzo[a,l]pyrene) to 0.2 ng mL(-1) (dibenzo[e,l]pyrene).