Heavy atom induced room temperature phosphorescence: a tool for the analytical characterization of polycyclic aromatic hydrocarbons

We have developed a heavy atom induced room temperature phosphorescence (HAI-RTP) procedure for the analytical characterization of 15 polycyclic aromatic hydrocarbons (PAHs). This methodology is based on the measurement of the native RTP emission from the analytes. RTP measurements are made directly in fluid aqueous solution, without the need of a protective medium but in the presence of high concentrations of heavy atom perturbers. Efficient deoxygenation conditions should be ensured using sodium sulfite as the oxygen scavenger. In such conditions, 15 PAHs, identified as major pollutants by the Environmental Protection Agency (EPA), naphthalene, acenaphthylene, acenaphthene, fluorene, phenanthrene, anthracene, fluoranthene, pyrene, chrysene, benzo(a) anthracence, benzo(k)fluoranthene, benzo(b)fluoranthene, benzo(a)pyrene, indeno(1,2,3-cd)pyrene, benzo(g,h,i)perylene and dibenzo (a,h)anthracence, have been studied and analytically characterized using the proposed HAI-RTP procedure. To our knowledge, this is the first time that an analytically useful RTP emission of some of the PAHs under study in aqueous media has been observed. Once optimized the chemical variables affecting the phosphorescence phenomenon in solution, the phosphorescence spectral characteristic of all of the selected toxic compounds (excitation and emission wavelengths and triplet lifetimes) were obtained. Under the optimal experimental conditions, calibration graphs and detection limits (in the ng ml^-1 level) were established for the 15 PAHs under study. Potential applicability of the developed methodology will be discussed.