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Method TO-10A Pesticides/PCBs <br /> 15.3.3 The sampling system is activated and set at the desired sampling flow rate. The sample flow is <br /> monitored for 24 hours. <br /> 15.3.4 The PUF cartridge is then removed and analyzed as per Section 12. <br /> 15.3.5 A second sampler,unspiked,is collected over the same time period to account for any background <br /> levels of components in the ambient air matrix. <br /> 15.3.6 In general, analytical recoveries and collection efficiencies of 75%are considered to be acceptable <br /> method performance. <br /> 15.3.7 Replicate (at least triplicate) determinations of collection efficiency should be made. Relative <br /> standard deviations for these replicate determinations of f15%or less are considered acceptable performance. <br /> 15.3.8 Blind spiked samples should be included with sample sets periodically as a check on analytical <br /> performance. <br /> 15.4 Method Precision and Bias <br /> 15.4.1 Precision and bias in this type of analytical procedure are dependent upon the precision and bias of <br /> the analytical procedure for each compound of concern,and the precision and bias of the sampling process. <br /> 15.4.2 Several different parameters involved in both the sampling and analysis steps of this method <br /> collectively determine the precision and bias with which each compound is detected. As the volume of air <br /> sampled is increased,the sensitivity of detection increases proportionately within limits set by: (a)the retention <br /> efficiency for each specific component trapped on the polyurethane foam plug, and (b) the background <br /> interference associated with the analysis of each specific component at a given site sampled. The sensitivity of <br /> detection of samples recovered by extraction depends on: (a)the inherent response of the particular GC detector <br /> used in the determinative step, and(b) the extent to which the sample is concentrated for analysis. It is the <br /> responsibility of the analyst(s) performing the sampling and analysis steps to adjust parameters so that the <br /> required detection limits can be obtained. <br /> 15.4.3 The reproducibility of this method for most compounds for which it has been evaluated has been <br /> determined to range from f5 to±30% (measured as the relative standard deviation)when replicate sampling <br /> cartridges are used(N>5). Sample recoveries for individual compounds generally fall within the range of 90 to <br /> 110%,but recoveries ranging from 65 to 125%are considered acceptable. PUF alone may give lower recoveries <br /> for more volatile compounds(i.e.,those with saturation vapor pressures>10.3 mmHg). In those cases,another <br /> sorbent or a combination of PUF and Tenax TA(see Figure 2) should be employed. <br /> 15.5 Method Safety <br /> 15.5.1 This procedure may involve hazardous materials,operations,and equipment. This method does not <br /> purport to address all of the safety problems associated with its use. <br /> 15.5.2 It is the user's responsibility to consult and establish appropriate safety and health practices and <br /> determine the applicability of regulatory limitations prior to the implementation of this procedure. This should <br /> be part of the user's SOP manual. <br /> 16. References <br /> 1. "Standard Practice for Sampling and Analysis of Pesticides and Polychlorinated Biphenyls in Air,"Annual <br /> Book ofASTM Standards,Method D4861-94,ASTM,Philadelphia,PA. <br /> Page 10A-18 Compendium of MethodsJor Toxic Organic Air Pollutants January 1999 <br />