CARBON-DIOXIDE SUPERCRITICAL FLUID EXTRACTION WITH A REACTIVE SOLVENT MODIFIER FOR THE DETERMINATION OF POLYCYCLIC AROMATIC-HYDROCARBONS

The addition of commercially available derivatization reagents to two standard reference materials prior to supercritical fluid extraction (SFE) with carbon dioxide is evaluated for the analytical determination of polycylic aromatic hydrocarbons (PAHs). The addition of hexamethyldisilane (HMDS) and trimethylchlorosilane (TMCS) as a 2:1 mixture is found to enhance the extraction efficiency of PAHs from the National Institute of Standards and Technology (NIST) standard reference material 1649 and the National Research Council of Canada (NRCC) standard reference material HS-3. Using phenanthrene, fluoranthene, pyrene, and chrysene as sample compounds, extraction with the reactive modifier is found to be about six times more efficient than CO2alone and about two times more efficient than CO2modified with 10% methanol. The derivatization reagent displaces the analyte from the surface of the matrix. Values obtained with CO2modified with the derivatizing reagent compare well with those obtained from the standard Soxhlet liquid extraction. In addition, SFE is accomplished in only 4 h and uses only 4 ml of liquid solvent. © Oxford University Press 1993.