5.1 Ethers, alcohols, and other oxygenates can be added to gasoline to increase octane number and to reduce emissions. Type and concentration of various oxygenates are specified and regulated to ensure acceptable commercial gasoline quality. Drivability, vapor pressure, phase separation, exhaust, and evaporative emissions are some of the concerns associated with oxygenated fuels.

5.2 This test method is applicable to both quality control in the production of gasoline and for the determination of deliberate or extraneous oxygenate additions or contamination.

1.1 This test method covers the determination of ethers and alcohols in gasolines by gas chromatography. Specific compounds determined are methyl tert-butylether (MTBE), ethyl tert-butylether (ETBE), tert-amylmethylether (TAME), diisopropylether (DIPE), methanol, ethanol, isopropanol, n-propanol, isobutanol, tert-butanol, sec -butanol, n-butanol, and tert-pentanol (tert-amylalcohol).

1.2 Individual ethers are determined from 0.20 mass % to 20.0 mass %. Individual alcohols are determined from 0.20 mass % to 12.0 mass %. Equations used to convert to mass % oxygen and to volume % of individual compounds are provided. At concentrations <0.20 mass %, it is possible that hydrocarbons may interfere with several ethers and alcohols. The reporting limit of 0.20 mass % was tested for gasolines containing a maximum of 10 volume % olefins. It may be possible that for gasolines containing >10 volume % olefins, the interference may be >0.20 mass %. Annex A1 gives a chromatogram showing the interference observed with a gasoline containing 10 volume % olefins.

1.3 This test method includes a relative bias correlation for ethanol in spark-ignition engine fuels for the U.S. EPA regulations reporting based on Practice D6708 accuracy assessment between Test Method D4815 and Test Method D5599 as a possible Test Method D4815 alternative to Test Method D5599. The Practice D6708 derived correlation equation is only applicable for ethanol in fuels in the concentration range from 2.28 % to 14.42 % by mass as measured by Test Method D4815. The applicable Test Method D5599 range for ethanol is from 2.16 % to14.39 % by mass as reported by Test Method D5599.

1.4 Alcohol-based fuels, such as M-85 and E-85, MTBE product, ethanol product, and denatured alcohol, are specifically excluded from this test method. The methanol content of M-85 fuel is considered beyond the operating range of the system.

1.5 Benzene, while detected, cannot be quantified using this test method and must be analyzed by alternate methodology (see Test Method D3606).

1.6 The values stated in SI units are to be regarded as standard. Alternate units, in common usage, are also provided to increase clarity and aid the users of this test method.

1.7 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.