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Method TO-10A Pesticides/PCBs <br /> 14.2.2 A standard solution of the compound of interest is prepared in a volatile solvent(i.e.,hexane,pentane, <br /> or benzene). A small,accurately measured volume(i.e., 1 mL)of the standard solution is placed into the modified <br /> midget impinger. The sampler pump is set at the rate to be used in field application and then activated. Nitrogen <br /> is drawn through the assembly for a period of time equal to or exceeding that intended for field application. After <br /> the desired sampling test period,the PUF plugs are removed and analyzed separately as per Section 12. <br /> 14.2.3 The impinger is rinsed with hexane or another suitable solvent and quantitatively transferred to a <br /> volumetric flask or concentrator tube for analysis. <br /> 14.2.4 The sampling efficiency(SE)is determined using the following equation: <br /> % SE = Wl x 100 <br /> Wo - Wr <br /> where: <br /> W, = amount of compound extracted from the primary trap,ng. <br /> Wo= original amount of compound added to the impinger,ng. <br /> Wr= residue left in the impinger at the end of the test,ng. <br /> 14.2.5 If material is found in the secondary trap, it is an indication that breakthrough has occurred. The <br /> addition of the amount found in the secondary trap,W2,to W,,will provide an indication for the overall sampling <br /> efficiency of a tandem-trap sampling system. The sum of W,,W2(if any),and Wr must equal(approximately <br /> f 10%)Wo or the test is invalid. <br /> 14.2.6 If the compound of interest is not sufficiently volatile to vaporize at room temperature,the impinger <br /> may be heated in a water bath or other suitable heater to a maximum of 50°C to aid volatilization. If the <br /> compound of interest cannot be vaporized at 50°C without thermal degradation,dynamic retention efficiency <br /> (REd)may be used to estimate sampling efficiency. Dynamic retention efficiency is determined in the manner <br /> described in Section 14.2.7. Table 7 lists those organochlorine pesticides which dynamic retention efficiencies <br /> have been determined. <br /> 14.2.7 A pair of PUF plugs is spiked by slow,dropwise addition of the standard solution to one end of each <br /> plug. No more than 0.5 to 1 mL of solution should be used. Amounts added to each plug should be as nearly <br /> the same as possible. The plugs are allowed to dry for 2 hours in a clean,protected place(i.e.,desiccator). One <br /> spiked plug is placed in the primary trap so that the spiked end is at the intake and one clean unspiked plug is <br /> placed in the secondary trap. The other spiked plug is wrapped in hexane-rinsed aluminum foil and stored in a <br /> clean place for the duration of the test(this is the static control plug, Section 14.2.8). Prefiltered nitrogen or <br /> ambient air is drawn through the assembly as per Section 14.2.2. <br /> [Note: Impinger may be discarded.] <br /> Each PUF plug(spiked and static control)is analyzed separately as per Section 12. <br /> 14.2.8 This dynamic retention efficiency(%REd)is calculated as follows: <br /> % RE = jW—�1 x 100 <br /> 0 <br /> where: <br /> W, = amount of compound recovered from primary plug,ng. <br /> Page 10A-16 Compendium of Methodsjor Toxic Organic Air Pollutants January 1999 <br />