Detection of polychlorinated biphenyls by photoactivated fluorescence and by sensitized laser photolysis

Fluorescence resulting from the photoactivated reaction between polychlorinated biphenyls (PCBs) and diphenylamine in isopropanol solution was exploited for PCB detection. Photoactivation was performed in 10 min with 252 nm light from a xenon arc lamp; the same light source, filtered at 365 nm, provided the excitation energy during fluorescence monitoring. Small-volume cuvettes were fabricated to enable analysis of 5 μl samples, and a glass fiber bundle was used to transmit the total emission for detection with a photomultiplier tube to attain a detection limit of 0.1 μg/ml. Sensitization of the PCB photolysis was also investigated by introducing phenothiazine to the reacting solution. A helium-cadmium laser system accomplished the sensitized photolysis in 5 min and the resulting fluorescence was monitored with a fluorometer to allow analysis of 50 μl samples at 0.05 μg/ml. Both techniques can differentiate between PCBs and non-PCB oil and have been demonstrated to be applicable for analyzing extracts from spiked soil samples.