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f <br /> 3 <br /> No chlorobenzene or dichlorobenzenes were detected in any samples <br /> at a limit of detection of 0.1 ug/g. This result does not agree <br /> with results of analyses of samples previously collected at this <br /> site by American Environmental Management and analyzed by Eureka <br /> Laboratories (Report to American Environmental Management Corp. <br /> from Eureka Laboratories dated July 8, 1986.) . Because there are <br /> so many petroleum related compounds which appear in the <br /> chromatograms from these samples, and because the photoionization <br /> detector is non-specific detector, a miss-identification of the <br /> analytes could have occurred in the previous determination. No <br /> confirmatory work was done at that time. To confirm the absence ' <br /> of chlorinated materials in these samples, in addition to <br /> analyseswith the mass selective detector in the specific ion <br /> mode, extracts from four of the samples were analyzed by high <br /> resolution gas chromatography/mass spectrometry. No halogenated <br /> materials were detected. Results from samples fortified with <br /> chlorobenzene and the dichlorobenzene, discussed below under <br /> Quality Assurance show that these compounds would have been <br /> detected if they had been present in the samples. <br /> 4ualityAssurance <br /> lecause the soil cores were not homogenized before sub-sampling <br /> to prevent loss of volatile components some variability in <br /> results of analyses of sub-samples from the same core was <br /> expected. To determine the variability in the analysis for the <br /> components of interest, duplicate sub-samples of four of the soil <br /> cores were extracted and analyzed. Results of analysis of <br /> extracts from duplicate sub-samples from the same core show up to <br /> approximately 501 variation in levels of analytes measured. <br /> To confirm that the extraction and analysis methods used on the <br /> samples were valid for the analytes of interest, sub-samples of <br /> several cores were 'fortified with diesel and the aromatic <br /> volatile hydrocarbons prior to extraction and analysis. Four <br /> sub-samples of soil from the top cores of R-2 and R-3 which <br /> contained none of the analytes were used for fortification. In <br /> addition, a sub-sample of the 301 section of R-1 which had been <br /> shown to contain diesel and several of the aromatic volatile <br /> hydrocarbons was also fortified. Results, shown in Table 2 <br /> indicate that recoveries were satisfactory for all analytes. <br /> Diana G. ' Gsham, Supervisor <br /> Physical/Environmental <br /> Analytical Section <br /> Sabrina C. Leung, Principal Res. Chemist <br /> Physical/Environmental <br /> Analytical Section <br /> f <br />