A GC–MS Purge-and-Trap Method Comparison Study for MTBE Analysis in Groundwater

ether (MTBE) determination in specific groundwater matrices. It demonstrates the importance of laboratory selection for compound analysis based upon technical experience and instrument capabilities. This method study was performed in support of a treatment technology demonstration for MTBE conducted under the EPA Superfund Innovative Technology Evaluation program. MTBE is an oxygenate added to gasoline for improved combustion performance. Regulatory concern about MTBE is increasing, and the demand is growing for analytical methods for detecting this compound in the environment. Oxygenates such as MTBE have significant water solubility, which can present a particular problem; for example, when MTBE is in groundwater and the sample preparation technique is a purge-and-trap procedure such as SW-846 Method 5030B. The primary concern with this approach is the purging efficiency of MTBE. Because MTBE is highly water soluble, purging this compound to separate it chemically from an aqueous matrix can be less effective than desired, and it could limit method sensitivity and cause low-biased results. Many researchers, however, have suggested that purge-and-trap methods can provide The U.S. Environmental Protection Agency has proposed the term demonstration of method applicability for the process of analytical method evaluation and selection under a performance-based measurement system approach, wherein methods are selected based on their demonstrated ability to meet project-specified performance criteria in the specific matrices of interest. Such a demonstration recently has been undertaken at the Ventura County Naval Base (Port Hueneme, California, USA). This study supported a treatment technology demonstration for methyl-tert-butyl ether (MTBE) in groundwater by assessing the ability of commercially available purge-and-trap gas chromatography–mass spectrometry methods to meet project sensitivity, precision, and accuracy criteria for MTBE and related oxygenate compounds in four groundwater matrices. A GC–MS Purge-and-Trap Method Comparison Study for MTBE Analysis in Groundwater