Evaluation of Methods Used to Desorb the Constituents Adsorbed on the Charcoal Contained in Automotive Evaporative Canisters. Part 2

摘要

The report presents the conclusion of a two-part study which evaluated current extraction methods for analyzing charcoal canisters used to control evaporative emissions in automobiles. The second part of the study investigated the use of solvent-free extraction methods such as high pressure CO2 soxhlet extraction and vacuum transfer extraction. The results of the solvent-free methods were then compared to the CS2 soxhlet extraction methods. The results of the study showed that the CS2 method extracted up to 8% more material (by weight) from the charcoal than did the vacuum transfer method and up to 15% more material (by weight) than did the high pressure CO2 soxhlet extraction method. In addition more total hydrocarbons were measured with the CS2 method than were measured in either the vacuum transfer or the high pressure CO2 methods. The high pressure CO2 soxhlet extraction method gave the lowest hydrocarbon measurements of the three methods.