Remediation of PAH-Contaminated Soils and Sediments: A ...

Sample Cleanup
After extraction, cleanup methods are used to reduce and or eliminate sample
interferences. Most soil and waste extracts require some degree of cleanup, but
cleanup for water extracts may be unnecessary.
For PAH analysis, the recommended cleanup methods are:
� Gel permeation chromatography (3640). This is the most universal
cleanup technique for a broad range of semivolatile organics. It is capable
of separating high molecular-weight, high boiling material from the sample
analytes. It has been used successfully for all the semivolatile base,
neutral, and acid compounds associated with the EPA Priority Pollutant
and the Superfund Target Compound list to clean up samples prior to
GC/MS analysis for semivolatiles and pesticides.
� Alumina (EPA 3610 and 3611). Method 3611 may be used for
fractionation of aliphatic, aromatic, and polar analytes.
� Florisil (EPA 3620)
� Silica gel (EPA 3630).
The decision process in selecting between the different options available
generally depends on the amount of interferences/high boiling material in the
sample extract and the degree of cleanup required by the determinative method.
For analysis with either the 8100/8310 determinative methods, the cleanup
methods 3611, 3630, and 3640 are preferred.
Analysis
Determination procedures include:
� EPA 8100 GC Packed and capillary column with FID (flame ionization
detector)
� EPA 8310 HPLC Reverse Phase with UV/ Fluorescence detectors.
� EPA 8270 GC MS
� EPA 8275 Thermal extraction/GC MS
� EPA 8410 GC, capillary column FT-IR
The Mass Spec procedures are generally more specific, but less sensitive than
the appropriate gas chromatographic (GC)/specific detection method. Many GC
methods with either selective or non-selective detectors are more appropriate for
use where the target analytes are known, are of limited number, and of
significantly greater concentration than potential interfering materials. When the
site where samples are taken from is not well characterized, and the researchers
are concerned about a large numbers of analytes, analysis by GC/MS or
HPLC/MS may be more appropriate.
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