Round-Robin Testing of a New EPA Dispersant Effectiveness Protocol

Abstract

ABSTRACT The current U.S. Environmental Protection Agency (EPA) protocol for testing the effectiveness of dispersants, the Swirling Flask Test (SFT), has been found to give widely varying results in the hands of different testing laboratories. A redesign of the testing flask by eliminating the side arm, incorporating baffles in the wall of the flask, and adding a stopcock at the bottom has been adopted to improve reproducibility in the hands of different operators. The new procedure is called the Baffled Flask Test (BFT). Similar to the original SFT, the test is relatively simple, requires minimum equipment, and involves a total time span of about 2.5 hours for testing four replicates on one of the two crude oils. Before EPA can adopt the BFT as the official protocol replacing the SFT, the newly developed test must undergo independent testing in the hands of commercial laboratories. Thus, to demonstrate its repeatability and reproducibility to support its adoption as the new EPA testing protocol, a round-robin test was conducted during the spring 2000 with eight independent laboratories. The participating laboratories were provided with all the supplies needed to conduct the BFT: baffled flasks, South Louisiana and Prudhoe Bay crude oils, six dispersant products, and the artificial seawater formulation used in the protocol. The laboratories were given specific, detailed instructions on how to conduct the tests for the dispersants, including all necessary quality assurance procedures. Results were reported back to EPA and the results were analyzed statistically to quantify repeatability and reproducibility. The paper discusses the data and presents the analysis showing the method's reproducibility.