09_AC_4
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braunintertec.com THE ANALYTICAL Vol. 5 Issue 4 A BRAUN INTERTEC PUBLICATION Autumn 2009 Analysis of Polychlorinated Biphenyls (PCBs) By Becky Bilek, Ph.D, Technical Director [email protected] PCB is an acronym for the Pakistan Cricket Board, but the PCB that we’re interested in as scientists studying the environment is the class of compounds known as Polychlorinated Biphenyls (PCBs). In order to be classified as a PCB, the structure of a chemical must have three characteristics: • The skeleton is composed of two benzene rings. • There are various numbers of chlorine and hydrogen atoms attached to the carbon rings. • The chemical formula representing the structure is C H Cl where x = 1 to 10. If you were to account for every possible combination that met these criteria, you’d find there are 209 different PCB compounds. Each unique PCB structure is called a congener. For example, the PCB congener 3,3’,4,4’-Tetrachlorobiphenyl has chlorine atoms in four of the 10 numbered positions, as specified in the diagram. Of the 209 congeners, about 130 were commercially produced by the Monsanto Company under the trade name Aroclor. Each Aroclor is a mixture containing specific concentrations of several PCB congeners. Because the concentrations of each congener are specified in the formulation, the ratio of individual congeners relative to others is consistent for each Aroclor produced. To distinguish between different mixtures a four digit number is used, for example Aroclor 1268. The first two digits specify the number of carbon atoms in the skeleton structure (equivalent to 12 for PCBs) and the last two digits specify the percentage of chlorine by mass (68 percent for this mixture). Several different Aroclor mixtures were produced for different applications. Note that Aroclor 1016 is an exception to the standard way PCB mixtures are named. Despite the U.S. ban on PCB production that began in the late 1970s, PCBs are commonly found in the environment. This is because their chemical structure is very stable and does not degrade easily. They are one of a number of chemicals identified as persistent organic pollutants. Their stability, among other properties, made them very useful as insulating fluids in transformers and capacitors and as plasticizers, among other applications. In addition to being toxic, PCBs are also known carcinogens and can penetrate skin and latex. Sampling In our laboratory, PCB Aroclor analysis is performed on samples of soil, water, oil and wipes. Sampling requirements are as follows: • Soil: one 4 oz. glass jar. • Water: one liter collected in an amber glass jar without preservative. An entire liter is used for the analysis, so when sampling, a second jar must be collected as a back-up in case of breakage, equipment malfunction or other problems. See PCBs—Continued on page 3 Chemical Structure of PCBs 3 2 2’ 3’ 4 4’ 5 6 6’ 5’ (Cl)n (Cl)n The possible positions of the chlorine atoms on the benzene rings are denoted by numbers assigned to the carbon atoms. (Information from: http://commons.wikimedia.org/wiki/File: Polychlorinated_biphenyl_structure.svg) Cl Cl Cl Cl 12 10-x x
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braunintertec.com
THE ANALYTICAL
Vol. 5 Issue 4 A BRAUN INTERTEC PUBLICATION Autumn 2009
Analysis of Polychlorinated Biphenyls (PCBs)By Becky Bilek, Ph.D, Technical [email protected]
PCB is an acronym for the Pakistan Cricket Board, but the PCB that we’re interested in as scientists studying the environment is the class of compounds known as Polychlorinated Biphenyls (PCBs). In order to be classified as a PCB, the structure of a chemical must have three characteristics: • The skeleton is composed of two benzene rings. • There are various numbers of chlorine and hydrogen atoms attached to the carbon rings. • The chemical formula representing the structure is C H Cl where x = 1 to 10.
If you were to account for every possible combination that met these criteria, you’d find there are 209 different PCB compounds. Each unique PCB structure is called a congener. For example, the PCB congener 3,3’,4,4’-Tetrachlorobiphenyl has chlorine atoms in four of the 10 numbered positions, as specified in the diagram.
Of the 209 congeners, about 130 were commercially produced by the Monsanto Company under the trade name Aroclor. Each Aroclor is a mixture containing specific concentrations of several PCB congeners. Because the concentrations of each congener are specified in the formulation, the ratio of individual congeners relative to others is consistent for each Aroclor produced. To distinguish between different mixtures a four digit number is used, for example Aroclor 1268. The first two digits specify the number of carbon atoms in the skeleton structure (equivalent to 12 for PCBs) and the last two digits specify the percentage of chlorine by mass (68 percent for this mixture). Several different Aroclor mixtures were produced for different applications. Note that Aroclor 1016 is an exception to the standard way PCB mixtures are named.
Despite the U.S. ban on PCB production that began in the late 1970s, PCBs are commonly found in the environment. This
is because their chemical structure is very stable and does not degrade easily. They are one of a number of chemicals identified as persistent organic pollutants. Their stability, among other properties, made them very useful as insulating fluids in transformers and capacitors and as plasticizers, among other applications. In addition to being toxic, PCBs are also known carcinogens and can penetrate skin and latex.
Sampling In our laboratory, PCB Aroclor analysis is performed on samples of soil, water, oil and wipes. Sampling requirements are as follows: • Soil: one 4 oz. glass jar. • Water: one liter collected in an amber glass jar without preservative. An entire liter is used for the analysis, so when sampling, a second jar must be collected as a back-up in case of breakage, equipment malfunction or other problems. See PCBs—Continued on page 3
Chemical Structure of PCBs
3 2 2’ 3’
4 4’
5 6 6’ 5’(Cl)n (Cl)n
The possible positions of the chlorine atoms on the benzene rings are denoted by numbers assigned to the carbon atoms. (Information from: http://commons.wikimedia.org/wiki/File:
Polychlorinated_biphenyl_structure.svg)
4 4’4 4’
n
4 4’
n n
4 4’
n
Cl Cl
Cl Cl
12 10-x x
2 braunintertec.com
Lab Manager’s Corner: Iowa Certification The Braun Intertec Analytical Laboratory has provided reliable results and fast turnaround times for more than 25 years. During this time we have been able to expand our service offerings and back up our experience by becoming certified by national and state agencies. Recently our laboratory received certification from the Iowa Department of Natural Resources to perform analyses for underground storage tanks, clean water act, and solid waste
and contaminated site projects. We are also certified in Minnesota,
By Steve Albrecht, Project [email protected]
The Total Maximum Daily Load (TMDL) is a calculation of the maximum pollutant load that a body of water can receive and still meet water quality standards. Determining TMDLs helps establish goals for pollution reduction that will allow for the continued use of a body of water.
Section 303(d) of the Clean Water Act requires that states develop TMDL calculations for bodies of water. Recently, Minnesota had 1,158 approved TMDLs, with an additional 575 pending approval. This information is being used to develop a list of impaired waters, and to also rank them. Water quality standards have been developed for a wide range of pollutants and a water body is judged as impaired if it fails any of the established criteria. Currently, there are about 2,575 impaired water listings in Minnesota. Because of the complex nature of natural bodies of water, most of the monitoring and restoration activities are based on watersheds, which in turn are bundled together into river basins.
The TMDL is calculated by taking several factors into consideration. It must include a margin of safety (MOS), which takes into account a water body’s natural and seasonal variations. Another factor that is included is the ability of a water body to assimilate the pollutants and the amount that exceeds that capacity. Once the TMDL is calculated for a body of water, steps can be taken to reduce loading through a variety of programs.
When it comes to TMDLs, pollution sources are broken into two categories: point sources and nonpoint sources. Point sources are
usually pipes that discharge material. These sources are regulated by the National Pollutant Discharge Elimination System (NPDES) and include wastewater treatment plants, animal feedlots, and some stormwater discharges. Nonpoint sources include more general causes of pollution, including urban and agricultural runoff, septic systems and aquifers. Funding is available for restoration activities or to conduct monitoring studies to develop TMDLs through the 2006 Clean Water Legacy Act. There also are Environmental Protection Agency (EPA) section 319 grants for studies and control measures for non-point sources. Point sources are controlled by the NPDES program.
The Braun Intertec Analytical Laboratory performs a wide variety of tests for water pollutants and can help you with TMDL analyses. For more information, please contact me at 952.995.2622.
Tom Wagner
The importance of Total Maximum Daily Loads
Water pollutants come from a variety of sources, including urban runoff.
North Dakota and Wisconsin. Please contact Craig Foxhoven, our quality assurance director, at 952.995.2630 to get a complete approved parameter list for our Iowa services.
Additionally, we continue to support Leadership in Energy and Environmental Design (LEED) initiatives by providing TO-15 air canister analyses. This is an air analysis for volatile compounds, and we have been seeing an increase in this service area. Also, as part of Braun Intertec’s commitment to environmental responsibility, we now offer this newsletter in an electronic format. If it would be more convenient for you to receive this newsletter via e-mail, please contact me at [email protected].
braunintertec.com 3
When it comes to work, Eric Warns thrives on variety. As a lab analyst I with the inorganic laboratory group, he’s responsible for a number of different analyses, including mercury, flash point, chemical oxygen demand (COD), ASTM’s sulfate soil method, and pH. He also works with the laboratory’s supply vendors and handles the majority of the supply ordering for the lab.
“Every day is different,” Eric said. “My favorite moment is when an analysis goes smoothly and everything falls into line and the quality assurance parameters are within specifications.”
Eric’s love of math and science led him to pursue a career in classical chemistry. He attended the University of Eau Claire and has been working in the laboratory for about a year. In his free time, Eric follows English soccer. He recently began to home brew, as well, and is currently constructing a liquor cabinet out of mahogany.
Meet Eric Warns
Chromatogram of PCB 1268
For all matrices, a solution containing surrogate compounds is added to the sample before it is extracted. The recoveries of these compounds will be an indication of the effectiveness of the extraction. • Soil samples are extracted by microwave (EPA Method 3546). • Water samples are extracted by separatory funnel (EPA Method 3510C). • Oil samples are diluted with hexane (EPA Method 3580A). • Wipe samples are degraded with sulfuric acid in a solution of hexane (EPA Method 3580A).
Sample Analysis Sample extracts are analyzed by gas chromatography using an
PCBs—Continued from page 1 In addition, for required laboratory quality control samples, two additional one liter jars for one water sample per group should be collected. • Oil: a volume of at least 25mL should be collected in a glass jar without preservative. • Wipe: a 2 oz. glass jar containing a gauze pad should be used. The gauze should be moistened with a small amount of hexane prior to wiping the surface area to be sampled.
Sample Preparation
electron capture detector following EPA Method 8082. Unlike many chromatographic analyses where a single peak is associated with each compound, in the analysis of PCBs the pattern of peaks in the results obtained is very important for identifying the specific Aroclor. An example of a chromatogram for a sample containing Aroclor 1268 is shown in the figure above. Because PCBs are mixtures of several compounds, the retention time for each peak in the mixture, as well as the relative amount of each compound (i.e., the size of the peaks relative to each other), aid in the identification.
While PCBs are no longer produced, due to their stability and widespread use, they will likely continue to be present in contaminated areas for quite some time.
Providing engineering and environmental solutions since 1957
©2009 Braun Intertec Corporation
Questions, Requests and Comments
Thomas Wagner, [email protected]
Steven Albrecht, [email protected]
Braun Intertec Corporation11001 Hampshire Avenue SMinneapolis, MN 55438
This newsletter contains only general information. For specific applications, please consult your engineering or environmental consultants and legal counsel.
Guess Who’s Coming to Lunch
Need to know the proper way to handle a sample? How about additional information on a test method, or a refresher about a sampling technique? Our scientists and project managers are available for training and brown bag presentations to provide you with information on a wide range of topics, including:
§ Analytical methods§ Gas Chromatography/Mass Spectrometry vs. Gas Chromatography§ Quality control samples—What are they and why are they analyzed?§ TO-15 Air Canister sampling/analysis§ Hexavalent chromium in air§ Sample collection and handling techniques§ Shipping requirements for samples§ A general overview of our environmental or industrial hygiene services§ A topic of your choice
We will come to your site, or if you prefer, will host the training presentation at our office and provide a tour of our analytical laboratory. For more information, contact Tom Wagner at 952.995.2650 or [email protected].
