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Laser spectroscopic methods as a means of determining water pollutants

The suitability of laser-induced fluorescence spectroscopy was evaluated as a method for the in-situ detection of water contaminants. For example, lead thallium, cerium, benzene, pyrene, toluene, xylene, naphtalene, and anthracene were investigated. The absorption-, fluorescence-, and excitation-spectra of each contaminant were measured in distilled water, artificial seawater and natural seawater as the examination of pollution spectra, that has been described in literature so far, does not characterize the contaminants dissolution in water. The chosen polycyclic aromatic hydrocarbons (PAHs) and heavy metals were excited by means of a frequency doubled dye laser, the latter being pumped by an excimer laser or by a frequency tripled Nd:YAG laser. The laser emitted radiation in the range from 220 nm to 400 nm. The fluorescence signal was recorded in the 230 nm to 600 nm range. The detection limits were in the ppb-range for the PAHs and in the ppm to ppb range for the heavy metals. Computer- simulations were applied to analyze the spectra of pollutant mixtures. They displayed a superimposition of the individual spectra. Discrete components of a mixture could be distinguished using this method. Finally, the influence of dissolved organic matter was investigated.