Chanan Sluszny

Classification and quantification of polycyclic aromatic hydrocarbons on quartz sand particles by direct Fourier transform imaging fluorescence

A new method for analysis of PAH contamination deposited on quartz sand was developed. It is based on direct observation of the UV-induced fluorescence using a microscope and a specially designed imaging spectrometer which provides full fluorescence spectra at each pixel. The method is fast and requires no sample preparation. Linear calibration plots were obtained for monocomponent contaminations and for simple PAH mixtures. Absolute detection limits of a few pg are reported, which correspond to bulk concentrations in the m gg ˇ 1 range. In addition to concentrations, the method provides microscopic chemical images of the contaminants, which may provide useful source characterization. # 1998 Elsevier Science B.V. All rights reserved.

Photochemical Study of Anthracene Crystallites by Fourier Transform Spectroscopic Imaging

Abstract Fourier transform–based spectroscopic imaging was used for direct, time-resolved, analysis of UV-irradiated anthracene crystallites. Well-resolved fluorescence spectra were obtained at a spatial resolution of 1 μm. The appearance of such photochemical by-products as dianthracene and anthraquinone was monitored throughout the irradiation experiments. Under deaerated conditions, photolysis of anthracene was accompanied by formation of dianthracene. When performed under aerated conditions, however, the spectral data indicated formation of both dianthracene and anthraquinone. Spectral features obtained for the directly monitored photolysis of anthracene are discussed in respect to the structural and compositional modifications in such crystallites. Capabilities of the spectral imaging device for the quantification of the photochemical products of anthracene are discussed.

Chemical Imaging for PAH Analysis in Particulate Materials

Abstract Chemical imaging is a new analytical science, related to a combination of spatial and chemical resolutions. Several new chemical imaging tools have been developed and applied to environmental analysis. The advantages of such methods, which provide simultaneous morphological/geometrical and chemical speciation, are pointed out and exemplified in several environmental analytical applications. These include fast analysis of PAH contaminated aerosols at low concentrations, analysis of contaminated quartz sand particles, as well as improvement of laser induced fluorescence detection of PAH compounds in natural water, in the presence of various microparticles. It is shown that chemical imaging has a considerable potential in environmental applications and can provide detailed and unique information when particulate materials are concerned.

Aging effects in analysis of polycyclic aromatic hydrocarbon aerosols

Polycyclic aromatic hydrocarbon (PAH) aerosols undergo time-de- pendent processes such as various aging effects and material loss due to sublimation. Therefore, when their analysis is delayed, the results may not properly represent the true environmental composition as sampled. Moreover, even when fast analysis is performed, one may still be interested in the initial concentration of these aerosols, at the moment of their formation. In both cases, a characterization of the time depen- dence of aerosol mass losses and other possible modifications is of interest. In this study we monitored these time-dependent processes for three different PAH aerosol particulates (anthracene, perylene, and pyrene). We applied two experimental tech- niques: Fourier transform spectral imaging microscopy (FT-SIM) and traditional HPLC analysis. The former provided a full fluorescence spectrum at each pixel of the particulate, as well as PAH identification and quantification. The chemical imaging information was also used for morphological characterization of the PAH aerosols, which was applied for developing of a simple mathematical model. The effect of the time-delay upon the actual aerosol mass can thus be estimated. The original (as-formed or as-sampled) aerosol mass can be calculated using the pro- posed empirical model.