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<br />The extraction bottles may be constructed from various materials, <br />depending on the analytes to be analyzed and the nature of the waste (see <br />Step 4.3.3). It is recommended that borosilicate glass bottles be used <br />' instead of other types of glass, especially when inorganics are of <br />concern. Plastic bottles, other than polytetrafluoroethylene, shall not <br />be used if organics are to be investigated. Bottles are available from a <br />' number of laboratory suppliers. When this type of extraction vessel is <br />used, the filtration device discussed in Step 4.3.2 is used for initial <br />liquid/solid separation and final extract filtration. <br />' 4.3 Filtration Devices: It is recommended that all filtrations be <br />performed in a hood. <br />' 4.3.1 Zero-Headspace Extraction Vessel (ZHE): When the sample <br />is evaluated for volatiles, the zero-headspace extraction vessel described <br />in Step 4.2.1 is used for filtration. The device shall be capable of <br /> supporting and keeping in place the glass fiber filter and bra able to <br />' withstand the pressure needed to accomplish separation (50 psi). <br /> NOTE: When it is suspected that the glass fiber filter has been ruptured, an <br />' in-line glass fiber filter may be used to f ilter the material within the <br /> ZHE. <br />' 4.3.2 Filter Holder: When the sample is evaluated for other than <br />volatile analytes, a filter holder capable of supporting a glass fiber <br />. filter and able to withstand the pressure needed to accomplish separation <br />> may be used. Suitable filter holders range from simple vacuum units to <br />~~ relatively complex systems capable of exerting pressures of up to 50 psi <br />or more. The type of filter holder used depends on the properties of the <br />t material to be filtered (see Step 4.3.3). These devices shall have a <br />minimum internal volume of 300 mL and be equipped to accommodate a minimum <br />filter size of 47 mm (filter holders having an internal capacity of 1.5 L <br />or greater, and equipped to accommodate a 142 mm diameter fi"Iter, are <br />' recommended). Vacuum filtration can only be used for wastes with low <br />solids content (<10 percent) and for highly granular, liquid-containing <br />wastes. All other types of wastes should be filtered using positive <br />' pressure filtration. Suitable filter holders known to EPA are shown in <br />Table 4. <br />4.3.3 Materials of Construction: Extraction vessels and <br />filtration devices shall be made of inert materials which will not leach <br />or absorb sample components. Glass, polytetrafluoroethylene (I~TFE), or <br />' type 316 stainless steel equipment may be used when evaluating the <br />mobility of both organic and inorganic components. Devices made of high- <br />density polyethylene (HDPE}, polypropylene (PP}, or polyvinyl chloride <br />(PVC) may be used only when evaluating the mobility of metals. <br />Borosilicate glass bottles are recommended for use over other types of <br />glass bottles, especially when inorganics are analytes of concern. <br />1 4.4 Filters: Filters shall be made of borosilicate glass fiber, shall <br />contain no binder materials, and shall have an effective pore size of 0.6 to <br />0.8-{cm or equivalent. filters known to EPA which meet these specifica':ions are <br />identified in Table 5. Pre-filters must not be used. When evaluating the <br />' mobility of metals, filters shall be acid-washed prior to use by rinsing with 1N <br />1312 - 3 Revision 0 <br />' November 1990 <br />