HWF NOTES ©
Testing for Pentachlorophenol as a Screening Procedure to Exclude PCDD's and PCDF's from Hazardous Waste Fuel
by David Constans and David Gossman
Background on Dioxins and Furans
There are a number of beneficial chemicals in which the term dioxin or furan is used in their descriptive name. The dioxins and furans generally referred to as extremely hazardous are the highly toxic by-products associated with the production of certain chemicals or products of incomplete combustion (PICs). There are over 200 compounds that are structurally similar, 75 are chlorinated dibenzo-p-dioxins, another 135 are different forms of furans.
For the purposes of examination of the stack emissions from combustors the EPA, in the BIF Methods Manual Section 4.0 Table 4.0-1, has limited the list to 11 compounds that are calculated into the toxic equivalent quantity (TEQ's). The most toxic of the chlorinated dibenzo-p-dioxins (2,3,7,8-tetrachloro-dibenzo-p-dioxin or 2,3,7,8-TCDD) is found as an unwanted contaminant produced during manufacture of certain chlorinated pesticides, most commonly polychlorinated phenol based pesticides, usually in the 1-2 ppm range. Virtually all of these types of pesticides have been removed from the market in the United States. Polychlorinated phenol based pesticides such as 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) have been banned. One of the last of these to be banned was pentachlorophenol.
The other sources of PCDD's and PCDF's are the combustion of organic materials (such as wood fires, automobile and diesel engines, structure fires, and incinerators of all types) and the chlorination of organic materials under certain conditions (such as the bleaching of wood pulp to make paper).
The most likely potential source of PCDD's and PCDF's in fuel burned in a cement kiln might be from contaminants in manufactured chemical products that contain polychlorinated phenols. A facility's Part A application lists the waste codes that are allowed to be accepted at the facility. This list of waste codes generally excludes the F020, F021, F022, F023, F026, F027 and F028 waste codes that would be likely to contain PCDD's and PCDF's.
Analytical Procedures for PCDD's and PCDF's
SW-846 Method 8280 is the determination method for PCDD's and PCDF's in wastes. The entire method is some 50 pages in length. Although the method has been proven for use on such materials as "still bottoms", "fuel oils" and "reactor residues", the method is not an easy or accurate method for use on waste fuels, nor can it be performed within a reasonable time period to be useful in screening batches of HWF for PCDD's and PCDF's. The "Scope and Application" section of the method states: "This method is recommended for use only by analysts experienced with residue analysis and skilled in mass spectral analytical techniques." In Section 3 titled "Interferences", the method describes some of the interferants: "...interfering chlorinated compounds such as PCB's and polychorinated diphenyl ethers which may be found in concentrations several orders of magnitude higher than that of the analytes of interest." (underlining added for emphasis). PCB's and polychorinated diphenyl ethers are not the only compounds to interfere with this analysis. Chlorinated waxes and resins are also a problem. The large amount of chlorinated solvents (relative to the analytical levels trying to be achieved) also interfere with the analytical method. These materials are frequently present in waste fuels.
The Use of Pentachlorophenol Analysis as a Screening Test for PCDD's and PCDF's
Pentachlorophenol (PCP) is a readily detected compound that can be consistently analyzed for in waste fuel down to about 0.5% concentration, perhaps as low as 0.1% with the proper equipment and methodology. Since PCDD's and PCDF's are suspected contaminants in pentachlorophenol material at about 1-2 ppm the effective screening level is about 10 ppb or lower. As stated earlier, PCP was one of the last polychlorinated phenol based pesticides to be banned. PCP was a widely used preservative for wood and wood pro- ducts. It was also used to preserve non-food starches, dextrins and glues and was used as an additive in herbicides as well as exterior paints and coatings.
The analysis of pentachlorophenol in waste fuel is an effective method of screening for PCDD's and PCDF's. Techniques using GC-FID and GC-MSD are available to screen for a broad class of volatile and semivolatile compounds including PCP. This method can consistently be accomplished by properly trained chemists and technicians in a minimum amount of time, generally within 30-40 minutes of sample receipt.