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Pesticides/PCBs Method TO-10A <br /> 4.3 Other Documents <br /> • Code of Federal Regulations,Title 40,Part 136,Method 604 <br /> 5. Definitions <br /> Note: Definitions used in this document and in any user prepared Standard operating procedures (SOPS) <br /> should be consistent with ASTMD1356, E260, and E355. All abbreviations and symbols are defined within <br /> this document at point of use.] <br /> 5.1 Sampling efficiency(SE)-ability of the sampling medium to trap analytes of interest. The percentage of <br /> the analyte of interest collected and retained by the sampling medium when it is introduced as a vapor in air or <br /> nitrogen into the air sampler and the sampler is operated under normal conditions for a period of time equal to <br /> or greater than that required for the intended use is indicated by%SE. <br /> 5.2 Retention efficiency(RE)-ability of sampling medium to retain a compound added(spiked)to it in liquid <br /> solution. <br /> 5.3 Static retention efficiency-ability of the sampling medium to retain the solution spike when the sample <br /> cartridge is stored under clean,quiescent conditions for the duration of the test period. <br /> 5.4 Dynamic retention efficiency(REd)-ability of the sampling medium to retain the solution spike when air <br /> or nitrogen is drawn through the sampling cartridge under normal operating conditions for the duration of the test <br /> period. The dynamic RE is normally equal to or less than the SE. <br /> 5.5 Retention time(RT)-time to elute a specific chemical from a chromatographic column,for a specific carrier <br /> gas flow rate,measured from the time the chemical is injected into the gas stream until it appears at the detector. <br /> 5.6 Relative retention time(RRT)-a rate of RTs for two chemicals for the same chromatographic column and <br /> carrier gas flow rate,where the denominator represents a reference chemical. <br /> 5.7 Surrogate standard-a chemically inert compound(not expected to occur in the environmental sample)that <br /> is added to each sample,blank, and matrix-spiked sample before extraction and analysis. The recovery of the <br /> surrogate standard is used to monitor unusual matrix effects, gross sample processing errors, etc. Surrogate <br /> recovery is evaluated for acceptance by determining whether the measured concentration falls within acceptable <br /> limits. <br /> 6. Interferences <br /> 6.1 Any gas or liquid chromatographic separation of complex mixtures of organic chemicals is subject to serious <br /> interference problems due to coelution of two or more compounds. The use of capillary or microbore columns <br /> with superior resolution or two or more columns of different polarity will frequently eliminate these problems. <br /> In addition, selectivity may be further enhanced by use of a MS operated in the selected ion monitoring(SIM) <br /> mode as the GC detector. In this mode,co-eluting compounds can often be determined. <br /> January 1999 Compendium of MethodsJor Toxic Organic Air Pollutants Page 10A-3 <br />