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0 D 46"- 03
<br />• material (geomedia) for 24 h. After 24 h, equilibrium between
<br />die solid and solution phase is presumed to occur. The
<br />concentration of solute remaining in solution is measured and
<br />the amount of solute adsorbed is calculated. Given that the
<br />mass of solid phase is known, the distribution coefficient for
<br />the specified experimental conditions can then be calculated.
<br />S. Sipaiicaoee and Use
<br />5.1 This test method is meant to allow for a rapid (24 h)
<br />index of a geomedia's sorption affinity for given chemicals or
<br />leachate constituents. A large number of samples may be run
<br />using this test method to determine a comparative ranking of
<br />those samples, based upon the amount of solute sorbed by the
<br />geomedia, or by various geomedia or leachate constituents.
<br />The 24-h time is used to make the test convenient and also to
<br />minimize microbial degradation which may be a problem in
<br />longer-timed procedures. While Kd values are directly appli-
<br />cable for screening and comparative ranking purposes, their
<br />use in predictive field applications generally requires the
<br />assumption that Kd be a fixed value.
<br />5.2 While this test method may be useful in determining
<br />24-h Kd values for nonvolatile organic constituents, interlabo-
<br />ratory testing has been carried out only for the nonvolatile
<br />inorganic species, arsenic and cadmium. However, the proce-
<br />dure has been tested for single laboratory precision with
<br />polychlorinated biphenyls (PCBs) and is believed to be useful
<br />for all stable and nonvolatile inorganic, and organic constitu-
<br />ents. This test method is not considered appropriate for volatile
<br />0 onstituents.
<br />5.3 The 24-h time limit may be sufficient to reach a
<br />steady-state Kd. However, to report this determination as a
<br />steady-state Kd, this test method should be conducted for
<br />intermediate times (for example, 12,18 and 22 h) to ensure that
<br />the soluble concentrations in the solution have reached a steady
<br />state by 24 It. Refer to Test Method D 4319 for an alternate
<br />procedure of longer duration.
<br />6. Interferences
<br />6.1 When dealing with solutes of unknown stability either in
<br />contact with the geomedia or when used as blanks, care must
<br />be taken to determine if volatilization, hydrolysis, photodeg-
<br />radation, microbial degradation, oxidation-reduction (for ex-
<br />ample, Crm+ to Cr) or other physicochemical processes are
<br />operating at a significant rate within the time frame of the
<br />procedure. The stability and hence loss from solution may
<br />affect the outcome of this procedure if the aforementioned
<br />reactions are significant. The compatibility of the method and
<br />the solute of interest may be assessed by determining the
<br />differences between the initial solute concentration (see 9.8)
<br />and the final blank concentration of the solute (see 9.15). If this
<br />difference is greater than the expected precision of the method
<br />(10 a/d), then the Kd value generated may be unreliable and
<br />must be carefully evaluated.
<br />7. Apparatus
<br />7.1 Agitation Equipment-The agitation equipment to be
<br />used is the rotary solid waste extractor' specified in Test
<br />Method D 3987.
<br />7.2 Phase Separation Equipment---A filtration apparatus
<br />made of materials compatible with the solutions being filtered
<br />and equipped with a 0.45-µm pore size membrane filter, or a
<br />constant temperature centrifuge capable of separating particles
<br />with diameters greater than 0.1 pm (see Section 9). If organic
<br />compounds are being measured, the filtration apparatus, cen-
<br />trifuge tubes etc., should be compatible with the compounds
<br />being measured (that is, glass or stainless steel). Sorption of
<br />solute onto the filtration membrane may be significant for some
<br />solutes, and must be evaluated by the use of blanks through all
<br />steps of the procedure.
<br />7.3 Containers-Round, wide-mouth bottles compatible
<br />with the rotary extractor (Test Method D 3987) and of compo-
<br />sition suitable to the nature of the solute(s) under investigation
<br />and the analysis to be performed will be used. For nonvolatile
<br />inorganic constituents, high-density, linear polyethylene bottles
<br />should be used with the size of the bottle dictated by sample
<br />size, and the need for the solution to occupy 70 to 80 % of the
<br />container volume (that is, 125 mL, 250 mL, or 2-L bottles for
<br />sample sizes of 5, 10, or 70 g respectively). For nonvolatile
<br />organic constituents, TFE-fluorocarbon, glass bottles, or stain-
<br />less steel containers with water-tight closures made of chemi-
<br />cally inert materials should be used with size requirements
<br />being the same as for nonvolatile inorganics. Containers should
<br />be cleaned in a manner consistent with the analyses to be
<br />performed. Samples of the solutions to be analyzed should be
<br />stored in similar chemically compatible bottles.
<br />7.4 Balance, having a minimum capacity of 70 g and a
<br />sensitivity of ±0.005 g shall be used.
<br />8. Reagents
<br />8.1 Purity of Reagents-Reagent grade chemicals shall be
<br />used in all tests. Unless otherwise indicated, it is intended that
<br />all reagents shall conform to the specifications of the American
<br />Chemical Society, where such specifications are available 4
<br />Other grades may be used, provided it is first ascertained that
<br />the reagent is of sufficiently high purity to permit its use
<br />without lessening the accuracy of the determination.
<br />81 Purity of Water- Unless otherwise indicated, refer-
<br />ences to water shall be understood to mean Type N reagent
<br />water of Specification D 1193.
<br />' DiaM=btone, B. T Burke, R. W., and Gamey E. L., "Improved Leach
<br />Measumnenb on solid Wastes," ASTM Standmduadon News, June 1982, pp.
<br />28-33.
<br />4 Reagent Chemicals, American Chemical Society Specifications, American
<br />Chemical Society, Washington, DC. For suggestions on the testing of reagents not
<br />listed by the American Chemical Society, see Analar Slant nis for Laboratory
<br />Chemicals, BDH Ltd, Poole, Dorset, U.IL, and the United States Pharmacopeia
<br />and National Formulary, U.S. Phismucopeisl Convention, Inc. (USPC), Rockville,
<br />MD.
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