You are here:
EVALUATION OF METHODS USED TO DESORB THE CONSTITUENTS ADSORBED ON THE CHARCOAL CONTAINED IN AUTOMOTIVE EVAPORATIVE CANISTERS--PART II
Citation:
Dropkin, D. EVALUATION OF METHODS USED TO DESORB THE CONSTITUENTS ADSORBED ON THE CHARCOAL CONTAINED IN AUTOMOTIVE EVAPORATIVE CANISTERS--PART II. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/3-90/013b (NTIS PB90188848).
Description:
This report presents the conclusion of a two-part study with evaluated current extraction methods for anaylizing in automobiles. The second part of this study investigated the use of solvent-free extraction methods such as high pressure C02 soxhlet extraction and vacuum transfer extraction. The results of the solvent free methods were then compared to the CS2 soxhlet extraction method. The results of this 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% 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 vacuum transfer or the high pressure CO2 methods. The vacuum transfer apparatus used for this study was a modification of the appa that had been used for a previous study. More of the higher molecular weight hydrocarbons mainly alkylated aromatics greater than carbon number 9, were measured in the extract obtained from the modified vacuum transfer apparatus than were measured in the extract from the previous method. Lower quantities, however, of the lower molecular hydrocarbons were measured than before. The high pressure CO2 soxhlet extraction method gave the lowest hydrocarbon measurements of the three methods.