Room-temperature excitation-emission phosphorescence matrices for the analysis of polycyclic aromatic hydrocarbons

JUAN A. ARANCIBIA; GRACIELA M. ESCANDAR

Lugo, España

Congreso; XII International Symposium on Luminescence Spectrometry – Detection Techniques in Biomedical, Environmental and Food Analysis; 2006

There is a strong need for developing high-performance methods for the determination of polycyclic aromatic hydrocarbons (PAHs) in environmental samples. Because PAHs bearing more than four benzene rings possess the highest carcinogenic activity, our interest was focused in the simultaneous determination of pyrene (PYR) and benzo[a]pyrene (BaP). These PAHs are listed by the Environmental Protection Agency (EPA) as priority pollutants, with special attention to their presence in both drinking and ground waters. The high sensitivity and selectivity provided by room-temperature-phosphorescence (RTP) techniques encouraged us to develop a method based in this type of signal for the resolution of mixtures of the above compounds. PYR and BaP present RTP in organized media within a highly overlapped spectral region. Therefore, we decided to overcome this disadvantage by increasing the dimensionality of RTP measurements in combination with the use of second-order algorithm exploiting the second-order advantage. Specifically, the present work describes the simultaneous phosphorimetric determination of both analytes through excitation-emission phosphorescence matrices (EEPMs) and second-order multivariate calibration. Parallel factors analysis (PARAFAC) calibration enabled us to determine both compounds at low concentration levels without the necessity of applying separation steps, as well as significantly reducing the experimental time. An artificial neural networks approach was carried aut to optimize the chemical variables which have an influence on the RTP emission of the studied analytes. The best signals were obtained in the presence of sodium dodecyl sulfate (as organized medium), Tl(I) (as heavy-atom) and Na2SO3 (as oxygen scavenger). The study demonstrates that the used strategy is able of correctly predicting the concentration of the analised compounds in the presence of others potentially interferent PAHs. The high-performance of the proposed method was established with the determination of both PYR and BaP in artificial and real water samples.