tert-butyl ether (MTBE) has been added to gasoline formulations in
recent years as an octane booster and anti-knock compound. It also reduces
carbon monoxide emissions. However, some questions have been raised about
its potential toxicity in the environment. For more information on MTBE, consult
the Cal EPA web site
and this EPA web site.
Therefore, interest has grown in how to analyze for MTBE along with
other gasoline compounds such as benzene, toluene, xylenes and ethylbenzene
(BTXE). EPA Method 8020, Aromatic Volatile Organics by Purge and Trap
GC/PID, is suitable for determining MTBE. WCAS has added MTBE
to our Method 8020 target list. However, as with other PID methods,
it is subject to interferences from the hydrocarbons
present in gasoline. Even second column confirmation can yield false positives,
due to the many different constituents of gasoline. For the detection of trace
MTBE in gasoline-contaminated soils or water, we recommend EPA Method
8260, which utilizes GCMS. GCMS gives unequivocal results for
MTBE due to its unique mass spectrum, which is easily distinguishable
from potentially interfering matrix components. The BTXE components
can also be measured in the same analysis, again without matrix interferences.
If you need to analyze for MTBE in samples that may be contaminated
with gasoline, give us a call to discuss your options.