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<br />nitric acid followed by three consecutive rinses with deionized distilled water <br />' (a minimum of 1-L per rinse is recommended). Glass fiber filters are fragile and <br />should be handled with care. <br />' 4.5 pH Meters: The meter should be accurate to ± 0.05 unii:s at 25'C. <br />4.6 ZHE Extract Collection Devices: TEDLAR~z bags or glass, stainless <br />steel or PTFE gas-tight syringes are used to collect the initial liquid phase and <br />the final extract when using the ZHE device. These devices Misted are <br />recommended for use under the following conditions: <br />4.6.1 If a waste contains an aqueous liquid phase or if a waste <br />does not contain a significant amount of nonaqueous liquid (i_e., <1 <br />percent of total waste), the TEDLAR~ bag ar a 600 mL syringe should be used <br />to collect and combine the initial liquid and solid extract. <br />4.6.2 If a waste contains a significant amount of nonaqueous <br />liquid in the initial liquid phase (i_e., >1 percent of total waste), the <br />syringe or the TEDLAR~ bag may be used for both the initial solid/liquid <br />' separation and the final extract filtration. However, analysts should use <br />one or the other, not both. <br />4.6.3 If the waste contains no initial liquid phase (is 100 <br />percent solid) or has no significant solid phase (is 100 percent liquid), <br />either the TEDLAR~ bag or the syringe may be used. If the syringe is used, <br />discard the first 5 mL of liquid expressed from the device. The remaining <br />aliquots are used for analysis. <br />4.7 ZHE Extraction Fluid Transfer Devices: Any device capable of <br />transferring the extraction fluid into the ZHE without changing the nature of the <br />extraction fluid is acceptable (e.a., a positive displacement or peristaltic <br />pump,.a gas-tight syringe, pressure filtration unit (see Step 4.3.2), or other <br />ZHE deevice). <br />4.8 Laboratory Balance: Any laboratory balance accurate to within ± <br />0.01 grams may be used (all weight measurements are to be within ± 0.1 grams). <br />4.9 Beaker or Erlenmeyer flask, glass, 500 mL. <br />1 4.10 Watchglass, appropriate diameter to cover beaker or Erlenmeyer <br />flask. <br />4.11 Magnetic stirrer. <br />' S.0 REAGENTS <br />5.1 Reagent grade chemicals shall be used in all tests. Unless <br />otherwise indicated, it is intended that all reagents shall conform to the <br />specifications of the Committee on Analytical Reagents of the American Chemical <br />' Society, where such specifications are available. Other grades may be used, <br />1 ZTEDLAR~ is a registered trademark of Du Pont. <br />1312 - 4 Revision 0 <br />NovE~mber 1990 <br />