Cleaning sorbents used in matrix solid-phase dispersion with sonication: application to the estimation of polycyclic aromatic hydrocarbons at ng/g levels in marine sediments.

This study shows that ultrasonic assisted extraction is a good practise for removing impurities from sorbents used for matrix-solid phase dispersion (MSPD). A previous washing of the sorbent with an organic solvent or mixture of solvents eliminates part of the interferences, but this treatment is not enough for the quantification of PAHs at ng/g levels. It is demonstrated that the determination of traces of polycyclic aromatic hydrocarbons (PAHs) in solid samples processed by matrix-solid phase dispersion (MSPD) may be severely affected by the presence of sorbent impurities. Different extraction solvents and sonication conditions have been tested, and on the basis of the results obtained a new approach is presented for cleaning sorbents typically used in MSPD such C(18), silica or Florisil. The utility of the described approach has been illustrated by analysing by liquid chromatography and fluorescence detection different marine sediments.