ASTM D7754-11e1

The analysis of trace oxygenates in automotive spark-ignition engine fuel has become routine in certain areas to ensure compliance whenever oxygenated fuels are used. In addition, test methods to measure trace levels of oxygenates in automotive spark-ignition fuel are necessary to assess product quality.

1.1 This test method covers the determination of trace oxygenates in automotive spark-ignition engine fuel. The method used is a multidimensional gas chromatographic method using 1,2-dimethoxy ethane as the internal standard. The oxygenates that are analyzed are: methyl-tertiary butyl ether (MTBE), ethyl-tertiary butyl ether (ETBE), diisopropyl ether (DIPE), methanol, tertiary-amyl methyl ether (TAME), n-propanol, i-propanol, n-butanol, i-butanol, tert-butyl alcohol, sec-butyl alcohol, and tert-pentanol. Ethanol is usually not measured as a trace oxygenate since ethanol can be used as the main oxygenate compound in finished automotive spark-ignition fuels such as reformulated automotive spark-ignition fuels. The concentration range of the oxygenates covered in the ILS study was from 10 µg/Kg to 2000 µg/Kg. In addition this method is also suitable for the measurement of the C5 isomeric alcohols (2-methyl-1-butanol, 2-methyl-2-butanol) present from the fermentation of ethanol.

1.2 The ethanol blending concentration for which this test method applies ranges from 1 to 15% by volume. Higher concentrations of ethanol coelute with methanol in the analytical column. Lower levels of ethanol, similar to the other oxygenate, can be calibrated and analyzed also. If higher ethanol concentrations are expected, the window cutting technique can be used to avoid ethanol from entering the analytical column and interfere with the determination of the other oxygenates of interest. Refer to Appendix X1 for details.

1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

1.3.1 Alternate units, in common usage, are also provided to increase clarity and aid the users of this test method.

1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.