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7.2.3 1 Adjust the electrodes in the clamps of the electrode holder so that, upon lowering thelectrodes into the beaker, the glass electrode will be immersed just deep enough into the clear supernatant solution to establish a good electrical contact through the ground-glass joint or the fiber-capillary hole. Insert the electrodes into the sample solution in this manner. For combination electrodes, immerse just below the suspension. 7.2.4 If the sample temperature differs by more than 2 •C from the buffer solution, the measured pH values must be corrected. 7.2.5 Report the results as "soil pH measured in water at_•E" where "_•C" is the temperature at which the test was conducted. 7.3 Sampled preparation and pH measurement of waste materials 7.3.1 1 To 20 g of waste sample in a 50-mL beaker, add 20 mL of reagent water, cover, and continuously stir the suspension for 5 min. Additional dilutions are allowed if working with hygroscopic wastes and salts or other problematic matrices. 7.3.2 Let the waste suspension stand for about 15 min to allow most of the suspended w ste to settle out from the suspension or filter or centrifuge off aqueous phase for pH easurement. NOTE: If the waste is hygroscopic and absorbs all the reagent water, begin the expe iment again using 20 g of waste and 40 mL of reagent water. NOTE: If the supernatant is multiphasic, decant the oily phase and measure the pH of the aueous phase. The electrode may need to be cleaned (Step 3.3) if it beco es coated with an oily material. 7.3.3 Adjust the electrodes in the clamps of the electrode holder so that, upon lowering the el ctrodes into the beaker, the glass electrode will be immersed just deep enough into th clear supernatant to establish good electrical contact through the ground- glass joint or t e fiber-capillary hole. Insert the electrode into the sample solution in this manner. For mbination electrodes, immerse just below the suspension. 7.3.4 If the sample temperature differs by more than 2 •C from the buffer solution, the m asured pH values must be corrected. 7.3.5 Report the results as "waste pH measured in water at_•C"where "_•C" is the tempera ure at which the test was conducted. 8.0 QUALITY CO TROL 8.1 Refer to Chapter One for the appropriate QC protocols. 8.2 Electrod s must be thoroughly rinsed between samples. 9.0 METHOD PER ORMANCE 9.1 No data rovided. 9045D - 3 Revision 4 November 2004