Asymetric least squares for fluorescence background reduction of octadecyl extraction membranes

CALLIMAG, K; GOICOECHEA, H C; WANG, H; CAMPIGLIA, A D

Lousville, USA

Congreso; Annual Meeting Federation of Analytical Chemistry and Spectroscopy Society (FACSS 2009); 2009

<!-- /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0cm; margin-bottom:.0001pt; mso-pagination:widow-orphan; mso-layout-grid-align:none; punctuation-wrap:simple; text-autospace:none; font-size:10.0pt; font-family:Arial; mso-fareast-font-family:"Times New Roman"; mso-bidi-font-family:"Times New Roman"; mso-fareast-language:ES;} @page Section1 {size:612.0pt 792.0pt; margin:70.85pt 3.0cm 70.85pt 3.0cm; mso-header-margin:36.0pt; mso-footer-margin:36.0pt; mso-paper-source:0;} div.Section1 {page:Section1;} --> A goal for the analysis of polycyclic aromatic compounds is to develop screening techniques that obviate costly, time-consuming and laborious chromatographic procedures. For their analyses in liquid samples, special attention has been given to the combination of solid-phase extraction (SPE) and solid-matrix room-temperature luminescence spectroscopy (SMRTLS). The basic approach consists of extracting the organic compounds from the liquid sample with a solid material and measuring their luminescence (fluorescence and/or phosphorescence) on the solid substrate. The analytical merits include simple and rapid experimental procedures, adequate levels of detection and selectivity at the screening level. The methodology is well suited for portable instrumentation and field analysis. Because of the non-destructive nature of room-temperature luminescence measurements, extracting materials can be brought to the lab for subsequent specific compound identification via high-resolution techniques. One of the main drawbacks of SPE-SMRTLS techniques is the intense luminescence background observed from solid substrates. The presence of broad, featureless excitation and emission bands often interferes with analyte detection at relatively low concentration levels. Several attempts to reducing the luminescence background of solid substrates have been published in the literature. These include liquid extraction of luminescence impurities, ultraviolet irradiation of solid substrates and thin-layer chromatography. The research presented here fits within this context as it investigates a chemometric approach for fluorescence background correction of solid substrates. Asymmetric Least Squares (ALS) is applied to screening methodology for urine of mono-hydroxy polycyclic aromatic hydrocarbons (OH-PAH). PAH metabolites are directly determined on the surface of octadecyl extraction membranes via room-temperature fluorescence (RTF) spectroscopy. The application of ALS to SPE-RTF improved the limits of detection of OH-PAH by approximately two orders of magnitude. 2-hydroxy-fluorene, 1-hydroxy-pyrene, 3-hydroxy-benzo[a]pyrene and 9-hydroxy-phenanthrene were determined at the parts-per-trillion level with only 10mL of urine sample.