Types of Analysis to Detect Polychlorinated Biphenyls (PCB's)

Ask the Expert Question:

What types of analysis can be used to detect Polychlorinated Biphenyls (PCB’s)?

Experts Response:
PCB’s are normally reported on the basis of Aroclors, but can also be reported as congeners or homolog totals. The following will provide information on each.

Aroclors- Usually, seven to nine commercial mixes are evaluated and reported as total concentration for each Aroclor. This is always done by EPA Method 8082. There are some subtle differences among laboratories, but generally, the detection limit is determined by a statistical MDL, based on the analysis of seven low-spiked blanks. The RL must generally be above the MDL (usually by a minimum factor of 3), and must be supported by a valid calibration point. It is not uncommon for typical MDL’s to run from 0.1 to 0.5 ug/L, with RL’s running about 1 ug/L. This is the least expensive option for testing PCB’s.

Individual Congeners- Usually 12 to 64 individual compounds can be reported by method 8082 or the NOAA Status and Trends method.  As above for aroclors, detection limits are generally determined by a statistical MDL.  The RL must generally be above the MDL and must be supported by a valid calibration point. It is not uncommon for typical MDL’s to run from 0.3 to 0.8 ng/L, with RL’s running about 1 ng/L. This is the least expensive option for testing PCB’s congeners, although the price is considerably higher than PCB aroclors (above).

All 209 congeners, or any subset of them are also analyzed and reported by EPA Method 1668A or 1668B. The detection limit used here is a sample-specific signal-to-noise measurement performed for each analyte on the actual sample. Average detection limits run around 0.005 ng/L. Typical RLs run from 0.02 to 0.2 ng/L. This method is the most comprehensive and provides the lowest detection limits.  As a result, it is also the most expensive option for PCB analysis.

Homolog totals- These can be reported by a modification of EPA Method 8270. A homolog total is a result for all the congeners at a given level of chlorination. Typical detection limits from 0.0025 to 0.02 ug/L for individual homolog totals. The RL for the total of all homologs is 1 ug/L. This is the medium cost option compared with the other two methods.

If lower RL’s are needed, TestAmerica has a variety of options that can be explored such as higher sample volumes, clean hands/dirty hands techniques, etc.  These usually involve some modification to your sampling plan.