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1011 D 4646 - 03 <br />11.6 Note and report negative Kd values when and if they <br />occur. Negative Kd values may occur if the geomedia contains <br />the test solute prior to the application of the method. <br />11.7 It is suggested that the pH of the sorbent-solute mixture <br />be determined prior to separating the sorbent from the liquid <br />and reported where feasible. <br />12. Precision and Bias <br />12.1 An interlaboratory round-robin test was conducted at a <br />soil-to-solution ratio of 1:20 using 70.0 g of soil. Intralabora- <br />tory testing using a 1:20 soil-to-solution ratio was carried out <br />with no significant loss of precision for soil masses of 5.00, <br />10.0, and 70.0 g. Therefore, it is specified that the soil-to- <br />solution ratio be 1:20 with the working mass of soil (on an <br />oven-dried basis) between 5 and 70 g. <br />12.2 Precision: <br />12.2.1 The precision of this test method is limited by the <br />ability to obtain a homogeneous sample of geomedia, and the <br />precision of the various methods used to carry out the <br />procedure (that is, mass determinations, initial and 24-h <br />concentration of constituents). <br />12.2.2 A comprehensive overall precision statement, cover- <br />ing all species, is not feasible. Interlaboratory testing of this <br />procedure, using cadmium and arsenic as sorbates, with five <br />independent laboratories, and single laboratory testing with <br />PCBs indicated that a coefficient of variation of less than 10 % <br />is obtainable. <br />12.2.3 For a summary of interlaboratory testing for the 24-h <br />batch-type Kd determination see Table 1. <br />TABLE 1 Summary of Interlaboratory Testing for the 24-h Batch- <br />Type Kd Determination <br />Soil1 Soil1 Soil2 Soil3 Soil4 <br />Initial Concentration, pg/mL <br />10 200 100 100 100 <br />Cadmium Carbonate (as <br />CdC03): <br />X Kd, mL/g 1568 96.3 69.50 69.74 28.94 <br />Standard deviation, mUg ±156 16.32 17.73 17.87 ±2.64 <br />Coefficient of variation, % 9.95 6.56 11.13 11.29 9.14 <br />Number of replicates 12 12 10 12 9 <br />Arsenic (as KH2AsO,i): <br />X Kd, mUg 15.42 2.75 4.95 3.25 2.99 <br />Standard deviation, mUg ±0.92 ±0.85 ±0.27 ±0.26 ±0.20 <br />Coefficient of variation, % 5.99 30.9 5.53 7.88 6.52 <br />Number of replicates 12 12 12 12 12 <br />12.2.4 For a summary of single laboratory testing for an <br />organic solute see Table 2. <br />12.3 Bias-A determination of the bias for this procedure is <br />not possible since no standard soil or alternate technique exists. <br />TABLE 2 Summary of Single Laboratory for an Organic Solute <br />Soil 1" Soil 1 e Soil 2° Soil 2° <br />Initial Concentration, pg/mL 0.216 0.187 0.216 0.187 <br />(0 /o Ace- (20 /o (0 /o Ace- (20 % <br />tone) Acetone) tone) Acetone) <br />PCBs_Sas Aroclor 1242): <br />X Kd, mL/g 798 78.62 23.83 2.28 <br />Standard deviation, mUg +_"18.41 ±3.45 ±1.48 '0.11 <br />Coefficient of variation, % 2.31 4.39 6.21 4.82 <br />Number of replicates 4 4 4 4 <br />A Soil 1-Catlin silt loam. <br />a Soil 2-Sangamon paleosol. <br />c Soil 3-Kaolinite clay. <br />° Soil 4-Vandalia till, unaltered phase <br />ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentioned <br />in this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the risk <br />of infringement of such rights, are entirely their own responsibility. <br />This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years and <br />ifnotrevised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standards <br />and should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of the <br />responsible technical committee, which you may attend. If you feel that your comments have not received a fair headng you should <br />make your views known to the ASTM Committee on Standards, at the address shown below. <br />This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, <br />United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the above <br />address or at 610-832-9585 (phone), 610-832-9555 (fax), or service@astm.org (e-mail); or through the ASTM website <br />(www.astm.org). <br />Copyright by ASTM Intl (all rights reserved); Thu Jun 26 16:41:13 EDT 2008 <br />Downloaded/printed by <br />Camp Dresser Mc Kee pursuant to License Agreement. No further reproductions authorized.