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EPA Response to BP Spill in the Gulf of Mexico

Methods for Detecting Dispersants in Water

In response to the BP oil spill, EPA monitored air, water, sediment, and waste generated by the cleanup operations. Ongoing response and restoration efforts are posted to RestoreTheGulf.gov.

While emergency response data collection has ended, results continue to be available on this site. Any new data will continue to be posted to this site, and data will continue to be available here for the foreseeable future.

Much of the content of this site continues to be available for historical and information purposes, but we are no longer updating these pages on a regular basis.

Summary of EPA Analytical Methods for Dispersant Analysis in Water Samples

EPA is analyzing water samples associated with the BP oil spill to determine if any dispersant-related chemicals can be detected. Some of the chemical analyses use existing EPA methods that EPA slightly modified to enhance the performance of the method for the particular chemical. Other chemicals required the creation of new methods which EPA developed. The chart below summarizes EPA’s preferred analytical methods for dispersant-related compounds in water. The table includes modified methods taken from EPA's "Test Methods for Evaluating Solid Waste, Physical/Chemical Methods", also known as SW-846. The table also includes the new methods developed at EPA. These new methods are currently being reviewed for posting on EPA’s website and will be available as soon as they are finalized.

Compound CAS Number EPA Method ID Technology Reporting Limits EPA Aquatic Life Benchmark
Propylene Glycol 57-55-6 EPA SW 846 Modified 8270 Direct Inject GC/MS 500 µg/L 500,000 µg/L
2-Butoxyethanol 111-76-2 EPA R5/6 LC Direct Inject LC/MS/MS 125 µg/L 165 µg/L
Di(Propylene Glycol) Butyl Ether 29911-28-2 EPA R5/6 LC Direct Inject LC/MS/MS 1 µg/L Not determined at this time
2-Ethylhexanol 104-76-7 EPA SW 846 Method 8260 Heated purge GC/MS 10 µg/L Not determined at this time
Dioctylsulfosuccinate, sodium salt 577-11-7 EPA RAM-DOSS LC/MS/MS 20 µg/L 40 µg/L
CAS:  Chemical Abstract Service number
LC/MS/MS:  Liquid Chromatograph with Tandem MassSpectrometry

Basis of Benchmarks:

Propylene glycol:
In the absence of a saltwater benchmark, EPA is applying the freshwater guideline from:  Canadian Council of Minister of the Environment.  1999.  Canadian water quality guidelines for protection of aquatic life: glycols -- ethylene glycol, propylene glycol, diethylene glycol.  In:  Canadian environmental quality guidelines, 1999, Canadian Council of Minister of the Environment, Winnipeg.

Wess, J., H. Ahlers, and S. Dobson.  1998.  2-Butoxyethanol, Concise International Chemical Assessment Document 10.  World Health Organization (WHO), Geneva.  WHO lowest effect concentration (48-hr LC50, fish) = 165,000 μg/L.  WHO safety factor = 1000.  WHO PNEC = 165 μg/L

Dioctylsulfosuccinate, sodium salt:
In the absence of any other available criterion or guideline, EPA calculated this benchmark from effects concentrations compiled in EPA's Ecotox database using application factors equivalent to those recommended in the Great Lakes Water Quality Initiative Tier 2 criteria development approach.  Applied GLI Tier 2 to combined FW & SW despite lack of daphnid:  360 μg/L acute benchmark, 40 μg/L chronic benchmark.  Not far from Web ICE prediction of HC5=377 μg/L (implies 190 μg/L acute benchmark).

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