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GeoInsighter Winter 2002 Newsletter OXYGENATES AT THE FOREFRONT, AGAIN! Return to the Newsletter Index The Massachusetts Department of Environmental Protection (MADEP) issued its Final Policy on implementing It is likely that most of us will not see samples affected by this phenomena because the "typical" GC/MS analyses used for MTBE (i.e., USEPA Methods 8260B, 8021B, and 524.2 and MADEP VPH Method) do not heat the sample during purge and trap, so the potential for converting MTBE to TBA is non-existent. According to John Fitzgerald of the MADEP, detection and quantification of MTBE using an ambient temperature purge and trap technique is acceptable as long as the laboratory can demonstrate adequate MTBE recovery. In discussing this issue with several laboratories, they expect this to be a non-issue. However, data reviewers and decision makers should be diligent in validating MTBE results. It should also be noted that if low (i.e., less than 50 micrograms per liter) standards are ever adopted for alcohol oxygenates, in particular TBA, a heated purge and trap technique may be appropriate and precaution may then be warranted. Such standards do not appear to be on the foreseeable horizon according to Fitzgerald. Michael F. Dacey, P.G.,
L.S.P. Return to the Newsletter
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the volatile petroleum hydrocarbon/extractable petroleum hydrocarbon (VPH/EPH) approach last October. As the document has been evolving since 1994, significant changes were not anticipated for the final version. However, an overview of potential inaccuracies in identifying and quantifying methyl-tert-butyl ether (MTBE) with current volatile organic compound (VOC) analytical methods and recommendations for alternative methods is tucked away in Appendix 1 of the document that was not included in earlier versions. The MADEP follows guidance on analytical techniques summarized in an October 2002 edition of L.U.S.T.Line, a publication of the New England Interstate Water Pollution Control Commission. The primary issue is the hydrolysis of MTBE to tertiary butyl alcohol (TBA) during analysis of samples acidified to a pH less than 2 and analyzed using a heated purge and trap technique. The results may reflect underestimated MTBE concentrations and overestimated MTBE degradation product (TBA) concentrations. The L.U.S.T.Line article reports results of a United States Environmental Protection Agency (USEPA) study that showed 57 percent of MTBE was hydrolyzed to TBA in a sample preserved to a pH of 1 during analysis using a heated purge and trap technique.