Abstract
A unique method for screening polycyclic aromatic hydrocarbons (PAH) in soil samples is reported. Milligrams of soil are sonicated into the vial of a cryogenic fiber-optic probe with 250 μL of n-octane. Pollutants partition into the layer of extracting solvent and the cryogenic probe is then used for fluorescence measurements at liquid helium temperature (4.2 K). N-octane provides PAH with the appropriate Shpol'skii matrix to record highly resolved spectra and characteristic fluorescence lifetimes. Unambiguous PAH determination is directly performed from the layer of extracting solvent with no need for previous PAH separation. The total analysis time from the extraction to PAH identification is approximately 35 min per sample. Limits of detection are at the sub-parts per billion levels. PAH recoveries are similar to those obtained via high-performance liquid chromatography analysis. The simplicity of the experimental procedure, the short analysis time, the selectivity, and the excellent analytical figures of merit demonstrate the advantages of this approach for routine analysis of soil samples.
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