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Fluorescence quenched in ionic liquid
A room-temperature ionic liquid has proved to be an excellent solvent for the identification and discrimination of different classes of polycyclic aromatic hydrocarbons (PAHs) in a mixture. The group has examined the fluorescence quenching of five alternant and six nonalternant PAHs in the presence of nitromethane using 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF6]) as solvent. Alternant PAHs are fully conjugated systems, whereas the aromaticity of nonalternant PAHs is disrupted by five-membered rings. "We found that alternant PAHs are efficiently quenched by nitro-methane within [bmim][PF6], while nonalternant PAHs are not quenched at all. "PAHs are well-known carcinogens and mutagens that are released into the environment by incomplete combustion of fossil fuels and other materials. Separation and identification of individual PAHs in environmental samples has proved difficult, however," he said.
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