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�r� ,V n:r`. +�'�ar 9 �"�f.e 4Y• � RYJ s. L A' iH�. !""'I + <. d.- �r F .{r�� i'r ,. iCn�� -a "�� `�+�, rC,1�"� �+ � �7� �q�i� �T s�" ��' ', � Y.'�' ��'7• 1�� .� �+h �'�.'!Y. _ � ��b^� j _: F�:�r µ.r) :_ •i �` ';;,�?''�r�� rr F,: '�5'S',,.� �;"; `',+��d . �_rs ��y ;..,,� ,�. 1 � r� ¢�'�� , ��, �y��''*r�'-ri �; h '` w r:Iearnip. The extract may be further concentrated by using, the technique outlined in Paragraph 7,4.11 or adjusted to 10.0 mi, with the solvent last used. 7.4.11 Add a clean boiling chip and attach a two-ball micro- Snyder column to the concentrator tube. Prewet the column by adding approximately 0.5 mL of methylene chloride or exchange solvent through the top. Place the apparatus in the hot water bath. Adjust the vertical position and the water temperature, as required, to complete the concentration in 5-10 min. At the proper rate of distillation, the balls of the column will actively chatter, but the chambers will not flood. When the liquid reaches an apparent volume of approxirrately 0.5 mL, remove the apparatus from the water bath and allow to drain and cool for at least 10 min. Remove the micro-snyder column and rinse its lower joint into the concentrator tube with approximately 0.2 mL of appropriate solvent. Adjust the final volume to the volume required for cleanup or for the determinative method (see Table 1). 7.4.12 Transfer the concentrated extract to a clean screw-cap vial. Seal the vial with a Teflon-lined lid and marl: the level on the vial. Label with the sample number and fraction and store in the dark at 411C until ready for analysis or cleanup. 7.5 Extraction method for samples expected to contain hivh concentrations of organics (>20 mg/kg): 7.5.1 Transfer approximately 2 g (record weight to the nearest 0.1 g) of sample to a 20-mL vial, Wipe the mouth of the vial with a tissue to remove any sample material. Record the exact weight of sample taken. Cap the vias before proceeding with the next sample to avoid any cross contamination. 7.5.2 Add 2 g of anhydrous sodium sulfate to sample in the 20- mL vial and mix well. 7.5.3 Surrogate standards are added to all samples, spikes, and blanks (see Method 3500 for details on the surrogate standard solution and on the matrix spike solution). Add 2^0 mL of surrogate spiking solution to sample mixture, For the sample in each analytical batch selected for spiking, add 2.0 mL of the matrix: spiking standard. For base/neutral-acid analysis, the amount added of the surrogates and matrix spiking compo�.inds should result in a final concentration of 200 ng/uL of each base/neutral analyte and 400 ng/uL of each acid analyte in the extract to be analyzed (assuming a 1 ILL injection). if Method 3540, Gel-permeation cleanup, is