Method CARB 428

Determination of Polychlorinated Dibenzo-p-dioxin (PCDD), Polychlorinated Dibenzofuran (PCDF) and Polychlorinated Biphenyl Emissions from Stationary Sources

This method applies to the determination of polychlorinated dibenzo-p-dioxins (PCDD), polychlorinated dibenzofurans (PCDF) and polychlorinated bihenyls (PCB) in emissions from stationary sources at nanogram to picogram levels. This method can be used to determine PCDD/PCDF alone, PCBs alone, or both PCDDs/PCDFs and PCBs. The method calls for use of LRMS (low resolution mass spectrometry) for PCBs and either LR or HRMS for PCDDs/PCDFs.  Since the method was written, the HRMS method has become the option of preference for both PCDDs/PCDFs and PCBs in order to achieve the lowest detection limits possible.  The PCDDs/PCDFs determined are seventeen 2,3,7,8-substituted isomers considered to be the most toxic.  Total PCDDs/PCDFs by congener group (e.g. Total TCDD, PeCDD) are also reported.  Total mono- through deca- PCBs are reported for the PCBs.

Particulate and gaseous phase PCDD,s PCDFs and PCBs are extracted isokinetically from the stack and collected using a modified Method 5 sampling train consisting of a heated probe and filter holder, glass fiber or quartz filter,  XAD-2 resin trap, and a series of impingers.  The first and third impingers are left empty, the second impinger is filled with 100mL of D.I. water and the fourth is filled with 200-300g of silica gel. 

After collection, the filter is placed in a glass petri dish or bottle.  The probe, nozzle and front half of the filter holder is rinsed with acetone and/or methylene chloride followed by toluene.  The method calls for the use of methanol, benzene and methylene chloride rinses.  However, acetone and toluene are the more common rinse solvents used per similar US EPA methodologies.  Benzene, in particular, is no longer used for the rinse due to the hazards associated with this compound.  Per the method, the front half and back half train rinses are shipped back to the laboratory in separate containers.  The contents of the second and third containers are combined along with a D.I. water rinse of these impingers.

The method allows for the combined or separate processing of the front and back halve components of the train.  The water impingers and associated rinse do not need to be extracted if the analysis is for PCDDs/PCDFs only.  The water impingers must be extracted and analyzed for the analysis of the PCBs. 

Method Data

Hold Times, Preservatives, Preps, Collection, Analytical & Documentation
Holding Time:	None specified in the method. Simliar EPA methods require for PCBs 14 days from collection to extraction and 40 days from extraction to analysis and for PCDDs/PCDFs 30 days from collection to extraction and 45 days from extraction to analysis.
Preservatives:	None specified in method but in similar EPA methods requirements are to store samples at 4°C±2°C in the dark.
Required Preps:	Glass fiber filter free of organic binders and XAD-2 resin
Collection Method:	Modified Method 5 train following CARB 428 procedures.
Analytical Methodology:	HRGC/HRMS for PCDD/PCDFs and HRGC/LRMS for PCBs
Documentation:	CARB 428

* The analytes and detection limits listed for each method represent the typical detection limits and analytes reported for that particular method. Keep in mind that analyte lists may vary from laboratory to laboratory. Detection limits may also vary from lab to lab and are dependent upon the sample size, matrix, and any interferences that may be present in the sample.