DIOXETANE CHEMILUMINESCENCE DETECTION IN LIQUID-CHROMATOGRAPHY BASED ON PHOTOSENSITIZED ONLINE GENERATION OF SINGLET MOLECULAR-OXYGEN - A THOROUGH EXAMINATION OF EXPERIMENTAL PARAMETERS AND APPLICATION TO POLYCHLORINATED-BIPHENYLS

Experimental parameters influencing sensitivity and selectivity in chemiluminescence detection based on photoinduced production of singlet molecular oxygen in liquid chromatography, an approach introduced in earlier papers, are extensively studied. Normal-phase liquid chromatography is applied in addition to reversed-phase chromatography, using polychlorinated biphenyls (PCBs) as analytes. The photochemical reactor parameters play the most important role. The chemiluminescence detector parameters are generally restrained by the required photochemical reactor conditions. An alternative, commercially available, reagent for addition of singlet molecular oxygen (i.e., ethyl vinyl ether) and a new photochemical reactor construction are introduced and compared to the former ones. The experiments show that the optimum conditions are strongly determined by the individual PCB concerned. Planar PCBs known for their high toxicity, such as the PCBs 77, 126 and 169 can be detected far more sensitively than the non-planar ones. The inherent selectivity of the method is shown for a herring oil sample, spiked with the above PCBs, utilizing normal-phase liquid chromatography with a pyrenyl column.