COMPLIANCE INFO_2023 ARCADIS REPORT

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Method TO-10A Pesticides/PCBs 12. Analytical Procedure 12.1 Analysis of Organochlorine Pesticides by Capillary Gas Chromatography with Electron Capture Detector(GC/ECD) [Note: Organochlorine pesticides, PCBs and many nonchlorinated pesticides are responsive to electron capture detection(see Table 1). Most of these compounds can be analyzed at concentration of I to 50 ng/mL by GC/ECD. The following procedure is appropriate. Analytical methods that have been used to determine pesticides and PCBs collected from air by this procedure have been published(12).J 12.1.1 Select GC column(e.g., 0.3-mm by 30-m DB-5 column)and appropriate GC conditions to separate the target analytes. Typical operating parameters for this column with splitless injection are: Carrier gas- chromatography grade helium at a flow rate of 1 to 2 mL/min and a column head pressure of 7 to 9 psi(48 to 60 kPa);injector temperature of 250°C; detector temperature of 350°C; initial oven temperature of 50°C held for 2.0 min.,ramped at 15'C/min to 150'C for 8 min,ramped at 10°C/min to 295'C then held for 5 min;purge time of 1.0 min. A typical injection volume is 2 to 3 gL. 12.1.2 Remove sample extract from the refrigerator and allow to warm to room temperature. 12.1.3 Prepare standard solution from reference materials of known purity. Analytically pure standards of organochlorine pesticides and PCBs are available from several commercial sources. 12.1.4 Use the standard solutions of the various compounds of interest to determine relative retention times (RRTs)to an internal standard such as p,p'-DDE,aldrin or octachloronaphthalene. Use 1 to 3-gL injections or other appropriate volumes. 12.1.5 Determine detector linearity by injecting standard solutions of three different concentrations(amounts) that bracket the range of analyses. The calibration is considered linear if the relative standard deviation(RSD) of the response factors for the three standards is 20 percent or less. 12.1.6 Calibrate the system with a minimum of three levels of calibration standards in the linear range. The low standard should be near the analytical method detection limit. The calibration is considered linear if the relative standard deviation(RSD)of the response factors for the three standards is 20 percent or less. The initial calibration should be verified by the analysis of a standard from an independent source. Recovery of 85 to 115 percent is acceptable. The initial calibration curve should be verified at the begining of each day and after every ten samples by the analysis of the mid point standard;an RPD of 15%or less is acceptable for continuing use of the initial calibration curve. 12.1.7 Inject 1 to 3 ,uL of the sample extract. Record volume injected to the nearest 0.05,uL. 12.1.8 A typical ECD response for a mixture of single component pesticides using a capillary column is illustrated in Figure 6. If the response(peak height or area)exceeds the calibration range,dilute the extract and reanalyze. 12.1.9 Quantify PCB mixtures by comparison of the total heights or areas of GC peaks(minimum of 5)with the corresponding peaks in the best-matching standard. Use Aroclor 1242 for early-eluting PCBs and either Aroclor 1254 or Aroclor 1260 as appropriate for late-eluting PCBs. 12.1.10 If both PCBs and organochlorine pesticides are present in the same sample, use column chromatographic separation on silicic acid(5,6)prior to GC analysis. 12.1.11 If polar compounds are present that interfere with GC/ECD analysis,use column chromatographic cleanup or alumina,activity grade IV,in accordance with Section 11.2. 12.1.12 For confirmation use a second GC column such as DB-608. All GC procedures except GC/MS require second column confirmation. Page 10A-10 Compendium of MethodsJor Toxic Organic Air Pollutants January 1999