Combination of laser-induced fluorescence and diffuse-reflectance spectroscopy for the in situ analysis of diesel-fuel-contaminated soils.

Results of our laser-induced fluorescence (LIF) and diffuse-reflectance investigations of quartz sand and different soils spiked with Diesel fuel are reported. The LIF calibration functions, which were found to be significantly different for the various matrices, and the limits of detection were determined. For excitation at lambda(ex) = 266 nm, the limits of detection obtained ranged from 7 parts in 10(6) for quartz sand to approximately 200 parts in 10(6) for dark sand with organic matter and for dark peat. Furthermore, the diffuse-reflectance spectra of the matrices in the ultraviolet-near-IR range were determined. An attempt to correlate the slopes of the LIF calibration functions with the reflectances of the matrices is presented. The obtained normalized calibration functions are well suited to take into account relevant optical soil parameters and to reduce the variability of the LIF calibration behavior significantly.