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-F--roVv\ El4 � <br /> 1401, <br /> 1.2 There are various techniques by which these compounds may be introduced into the <br /> GC/MS system. The more common techniques are listed in the table above. Purge-and-trap, by <br /> Methods 5030 (aqueous samples) and 5035 (solid and waste oil samples), is the most commonly <br /> used technique for volatile organic analytes. However, other techniques are also appropriate and <br /> necessary for some analytes. These include direct injection following dilution with hexadecane <br /> (Method 3585) for waste oil samples; automated static headspace by Method 5021 for solid <br /> samples; direct injection of an aqueous sample (concentration permitting) or injection of a sample <br /> concentrated by azeotropic distillation (Method 5031); and closed system vacuum distillation (Method <br /> 5032) for aqueous, solid, oil and tissue samples. For air samples, Method 5041 provides <br /> methodology for desorbing volatile organics from trapping media (Methods 0010, 0030, and 0031). <br /> In addition, direct analysis utilizing a sample loop is used for sub-sampling from Tedlar® bags <br /> (Method 0040). Method 5000 provides more general information on the selection of the appropriate <br /> introduction method. <br /> 1.3 Method 8260 can be used to quantitate most volatile organic compounds that have <br /> boiling points below 200°C. Volatile, water soluble compounds can be included in this analytical <br /> technique by the use of azeotropic distillation or closed-system vacuum distillation. Such <br /> compounds include low molecular weight halogenated hydrocarbons, aromatics, ketones, nitriles, <br /> acetates, acrylates, ethers, and sulfides. See Tables 1 and 2 for analytes and retention times that <br /> have been evaluated on a purge-and-trap GC/MS system. Also, the method detection limits for 25- <br /> mL sample volumes are presented. The following compounds are also amenable to analysis by <br /> Method 8260: <br /> Bromobenzene 1,3-Dichloropropane <br /> n-Butylbenzene 2,2-Dichloropropane <br /> sec-Butylbenzene 1,1-D ich loropropene <br /> tert-Butylbenzene p-Isopropyltoluene <br /> Chloroacetonitrile Methyl acrylate <br /> 1-Chlorobutane Methyl-t-butyl ether <br /> 1-Chlorohexane Pentafluorobenzene <br /> 2-Chlorotoluene n-Propylbenzene <br /> 4-Chlorotoluene 1,2,3-Trichlorobenzene <br /> Dibromofluoromethane 1,2,4-Trimethylbenzene <br /> cis-1,2-Dichloroethene 1,3,5-Trimethylbenzene <br /> 1.4 The estimated quantitation limit (EQL) of Method 8260 for an individual compound is <br /> somewhat instrument dependent and also dependent on the choice of sample <br /> preparation/introduction method. Using standard quadrapole instrumentation and the purge-and-trap <br /> technique, limits should be approximately 5 Ng/kg (wet weight) for soil/sediment samples, 0.5 mg/kg <br /> (wet weight)for wastes, and 5 ug/L for ground water (see Table 3). Somewhat lower limits may be <br /> achieved using an ion trap mass spectrometer or other instrumentation of improved design. No <br /> matter which instrument is used, EQLs will be proportionately higher for sample extracts and <br /> samples that require dilution or when a reduced sample size is used to avoid saturation of the <br /> detector. <br /> 1.5 This method is restricted to use by, or under the supervision of, analysts experienced in <br /> the use of gas chromatograph/mass spectrometers, and skilled in the interpretation of mass spectra <br /> and their use as a quantitative tool. <br /> CD-ROM 8260B -4 Revision 2 <br /> December 1996 <br />