Determination of oxygenates in gasoline by GC x GC

Comprehensive two-dimensional gas chromatography (GC x GC) has been applied to the quantitation of oxygenates in reformulated gasoline. Target oxygena tes were C-1-C-4 alcohols, tert-pentanol, methyl tert-butyl ether (MTBE), d iisopropyl ether (DIPE), ethyl tert-butyl ether (ETBE), and tert-amyl methy l ether (TAME), These were separated from the gasoline matrix using a volat ility-based selectivity in the first chromatographic dimension, followed by a mixed-phase polarity/shape selectivity in the second dimension. The high resolving power of this stationary phase combination completely separated all oxygenates except DIPE, ETBE, and TAME, which exhibited coelution with other nonpolar gasoline components. Oxygenates quantitation was achieved wi th the use of an internal standard, an FID detector, and calibration curves , Quantitation results are in good agreement with ASTM and EPA standard met hods. When coupled with our previous method for BTEX and aromatics, a singl e GC x GC method can now quantitate MTBE, alcohols, BTEX, and aromatics in a one-hour analysis.