| Abstract
| - This paper explores the use of supercritical fluid extraction (SFE), in combination with various analyte collectionstrategies, for extracting energetic nitroaromatic compounds and their degradation products from soil samples.The required selectivity has been achieved by a combination of an SFE program and active trapping. Severaldifferent collection strategies were tested, using a selection of liquids (methanol, toluene, methyl tert-butyl ether,acetonitrile), inert and solid-phase extraction materials(Nexus, Oasis, LiChrolut), and 1-cm liquid chromatography precolumns (porous graphitic carbon, PGC). Thebest results were obtained using SFE in combination witha PGC precolumn. This setup allows on-line cleanup ofthe extract, and comparable results were obtained usingeither GC-ECD or GC-chemical ionization-MS for confirmatory analysis. The time required for a complete analysiswas less than 60 min, and only 1 mL of toluene wasneeded for a 0.5-g representative sample. In contrast, theEPA standard method 8330 required 18-h sonication and20 mL of acetonitrile for a 4.0-g sample and further timefor sample cleanup and HPLC analysis. The methodpresented here provides method detection limits in thelow-nanogram range, with relative standard deviationslower than 7%. The optimized method has been comparedand validated with EPA method 8330 in terms of efficiency parameters such as robustness, accuracy (trueness and precision), and capability of detection. Thevalidation demonstrated that the two analytical methodologies give comparable performance for the determination of nitroaromatic compounds, but SFE is superior foranalyzing amine degradation products.
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