Preparation Of Fluorescent Polysilsesquioxanes Film And Development For Detection Of Polychlorinated Biphenyls

Polychlorinated biphenyls (PCBs) are biphenyl derivatives comprised of209congeners with various degrees of chlorination. PCBs have a great physical and chemical stability and high boiling points, which allow their widespread production. Although PCBs have been banned from use due to their toxic, mutagenic and carcinogenic properties, they persist in the environment and have global environmental distribution. PCBs have been found in human tissues, animals, plants, birds, and bio magnifying in the food chain. As a kind of persistent organic pollutants (POPs), identification and quantitative analysis of PCBs have become an imminent task.Up to now, several detection methods have been proposed for PCBs, such as gas chromatography, high performance liquid chromatography and mass spectrometry; thin-layer chromatography and microscale methods. However, these methods are time-consuming and expensive as they require tedious sample pretreatment, sophisticated experimental instrumentation and performance. Therefore, it is still a big challenge to develop a rapid, highly sensitive and simple technique for screening PCBs.In comparison, the analytical method based on fluorescence spectroscopy shows advantages of simplicity, fast time response, high sensitivity, high spatial resolution and no need of references. Despite the fact that fluorescence is a highly sensitive, not much has been done with this method for the determination of PCBs. In the present study, a novel fluorescent film chemosensor for PCBs based on a fluorescence quenching sensing mechanism was designed. The prepared fluorescent polysilsesquioxane film with diphenylamine as a fluorescent probe is sensitive to PCBs in aqueous phase, including PCB1, PCB4, PCB18, PCB77and PCB101. The fluorescent chemosensor is a hybrid organic-inorganic functionalized polysilsesquioxane film which is prepared from y-(N,N-diphenylcarbamino)propyltriethoxysilane by sol-gel polymerization. The fluorescence emission intensity of the polysilsesquioxane film sensor decreased steadily with a corresponding increase of PCB77. PCBs efficiently quench the fluorescence of fluorescent chemosensor via a photo-induced electron transfer (PET) process. The detection limit of PCB77was found to be8.03×10-7mol/L. The obtained results show that the fluorescent sensor has a good thermal stability, high sensitivity and satisfactory reversibility sensing toward PCB77.