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 che miluminescence detection based on photoinduced production of singlet m olecular oxygen in liquid chromatography, an approach introduced in ea rlier papers, are extensively studied. Normal-phase liquid chromatogra phy is applied in addition to reversed-phase chromatography, using pol ychlorinated biphenyls (PCBs) as analytes. The photochemical reactor p arameters play the most important role. The chemiluminescence detector parameters are generally restrained by the required photochemical rea ctor conditions. An alternative, commercially available, reagent for a ddition of singlet molecular oxygen (i.e., ethyl vinyl ether) and a ne w photochemical reactor construction are introduced and compared to th e former ones. The experiments show that the optimum conditions are st rongly determined by the individual PCB concerned. Planar PCBs known f or their high toxicity, such as the PCBs 77, 126 and 169 can be detect ed far more sensitively than the non-planar ones. The inherent selecti vity of the method is shown for a herring oil sample, spiked with the above PCBs, utilizing normal-phase liquid chromatography with a pyreny l column.