Laserfiche WebLink
Method TO-10A Pesticides/PCBs <br /> samples. A field blank is treated exactly like a sample except that no air is drawn through the cartridge. Samples <br /> are stored at<4'C or below until analyzed in the laboratory. Extraction must occur within 7 days of sampling <br /> and analysis within 40 days of extraction. Refer to ASTM D4861-94(1),Appendix X3 for storage stability for <br /> various common pesticides and other compounds on PUF or PUF/Tenax TA sandwich. <br /> 11. Sample Extraction Procedure <br /> [Note: Sample extraction should be performed under a properly ventilated hood.] <br /> 11.1 Sample Extraction <br /> 11.1.1 All samples should be extracted within 1 week after collection. All samples should be stored at<4'C <br /> until extracted. <br /> 11.1.2 All glassware should be washed with a suitable detergent;rinsed with deionized water,acetone, and <br /> hexane;rinsed again with deionized water;and fired in an oven(500°C). <br /> 11.1.3 Prepare a spiking solution for determination of extraction efficiency. The spiking solution should <br /> contain one or more surrogate compounds that have chemical structures and properties similar to those of the <br /> analytes of interest. Octachloronaphthalene (OCN) and dibutylchlorendate have been used as surrogates for <br /> determination of organochlorine pesticides by GC with an ECD. Tetrachloro-m-xylene and decachlorobiphenyl <br /> can also be used together to insure recovery of early and late eluting compounds. For organophosphate pesticides, <br /> tributylphosphate or triphenylphosphate may be employed as surrogates. The surrogate solution should be <br /> prepared so that addition of 100 uL into the PUF plug results in an extract containing the surrogate compound <br /> at the high end of the instrument's calibration range. As an example,the spiking solution for OCN is prepared <br /> by dissolving 10 mg of OCN in 10 mL of 10% acetone in n-hexane, followed by serial dilution n-hexane to <br /> achieve a final spiking solution of OCN of 1 yg/mL. <br /> [Note: Use the recoveries of the surrogate compounds to monitor for unusual matrix effects and gross sample <br /> processing errors. Evaluate surrogate recovery for acceptance by determining whether the measured <br /> concentration falls within the acceptance limits of 60-120 percent.] <br /> 11.1.4 The extracting solution(5%diethyl ether/hexane)is prepared by mixing 1900 mL of freshly opened <br /> hexane and 100 mL of freshly opened diethyl ether(preserved with ethanol)to a flask. <br /> 11.1.5 All clean glassware,forceps,and other equipment to be used should be rinsed with 5%diethyl ether/ <br /> hexane and placed on rinsed(5%diethyl ether/hexane)aluminum foil until use. The condensing towers should <br /> also be rinsed with 5%diethyl ether/hexane. Then add 300 mL or 5%diethyl ether/hexane to the 500 mL round <br /> bottom boiling flask and add up to three boiling granules. <br /> 11.1.6 Using precleaned (i.e., 5% diethyl ether/hexane Soxhlet extracted) cotton gloves, the glass PUF <br /> cartridges are removed from the sealed container,the PUF removed from the glass container and is placed into <br /> the 300 mL Soxhlet extractor using prerinsed forceps. <br /> [Note: If"sandwich"trap is used, carefully clean outside walls of cartridge with hexane-soaked cotton swabs <br /> or laboratory tissues (discard) and place cartridge into extractor with intake (large end) downward.] <br /> 11.1.7 Before extraction begins,add 100 µL of the OCN solution directly to the top of the PUF plug. <br /> Page 10A-8 Compendium of Methodsjor Toxic Organic Air Pollutants January 1999 <br />