New methods to detect chlorinated organic pollutants in water.

摘要

The development of screening techniques for monitoring polychlorinated biphenyls (PCB), polychlorinated dibenzofurans (PDBF), and polycylic aromatic hydrocarbons (PAH) in aqueous samples is presented. The new methods are based on solid-liquid extraction room temperature phosphorimetry (SLE-RTP) and SLE-laser excited low temperature phosphorimetry (SLE-LELTP).; The basic approach for SLE-RTP consists of extracting the organic pollutants from the water sample with a non-polar solid material and measuring their phosphorescence emission directly from the solid substrate. The analytical merits include a simple and rapid experimental procedure, low levels of detection, and selectivity at the screening level. Our results demonstrate the feasibility to detect “total PCB” and “total PAH” contents at trace concentration levels in matrices of relatively simple composition. When SLE-RTP is combined to pattern recognition, a useful approach is obtained for screening “total PAH” and “total PCB contents” in heavily contaminated samples.; For the analysis of target compounds within the same pollutant class, we propose SLE-LELTP in Shpol'skii matrices. Micro liters of Shpol'skii solvent are spiked on the surface of the extraction membrane, and LELTP is directly performed on the solvent layer above the surface of the solid substrate. Phosphorescence measurements are easily performed with a fiber-optic cell specifically designed for cryogenic measurements at 77 K and 4.2 K. Because the pollutants partition into the layer of Shpol'skii solvent, highly resolved spectra are obtained for compound identification. The accuracy and precision needed for quantitative analysis in aqueous samples are demonstrated with a thorough investigation of quantitative parameters. It is shown that the analyte concentration in the layer of Shpol'skii solvent follows a linear relationship with the analyte concentration in the water sample. The same type of relationship is demonstrated for the phosphorescence signal of the cryogenic probe. The analytical figures of merit demonstrate feasibility to determine organic pollutants at the parts-per-trillion level with minimum solvent consumption.