ASTM D6293 Oxygenates and Paraffin, Olefin, Naphthene, Aromatic Hydrocarbon Types
ASTM D6293 Standard Test Method for Oxygenates and Paraffin, Olefin, Naphthene, Aromatic (O-PONA) Hydrocarbon Types in Low-Olefin Spark Ignition Engine Fuels by Gas Chromatography
1. Scope
1.1 This test method provides for the quantitative determination of oxygenates, paraffins, olefins, naphthenes, and aromatics in low-olefin spark-ignition engine fuels by multidimensional gas chromatography. Each hydrocarbon type can be reported either by carbon number (see Note 1) or as a total through C10, except for olefins, which can only be reported through C9. Higher boiling hydrocarbons cannot be reported by type and are reported as a composite group. The lower limit of detection for a single hydrocarbon component or carbon number type is 0.05 mass %.
NOTE 1 - There can be an overlap between the C9 and C10 aromatics; however, the total is accurate. Isopropyl benzene is resolved from the C8 aromatics and is included with the other C9 aromatics. Naphthalene is determined with the C11+ components.
1.2 This test method is applicable for total olefins in the range from 0.05 to 13 mass %. The test method can quantitatively determine olefins in samples where the olefin concentration does not exceed 0.6 % C4 or 4.0 % C5 or 4.5 % of the combined C4 and C5. Although the precision for benzene was determined in the range from 0.3 to 1.0 mass %, this test method can be used to determine benzene concentrations up to 5.0 mass %.
1.3 This test method is not intended to determine individual hydrocarbon components except for those hydrocarbon types for which there is only one component within a carbon number. Individually determined hydrocarbons are benzene, toluene, cyclopentane, propane, propylene, and cyclopentene.
1.4 Precision data has only been obtained on samples containing MTBE. Application of this test method to determine other oxygenates shall be verified in the user's laboratory. Methanol cannot be determined and shall be quantitated by an appropriate oxygenate method such as Test Method D4815 or D5599. Methanol is fully resolved and does not interfere with the determination of other components or groups.
1.5 Although specifically written for spark-ignition engine fuels containing oxygenates, this test method can also be applied to other hydrocarbon streams having similar boiling ranges, such as naphthas and reformates.
1.6 The values stated in SI units are to be regarded as the standard.
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.
2. Referenced Documents
2.1 ASTM Standards:
D4307 Practice for Preparation of Liquid Blends for Use As Analytical Standards
D4815 Test Method for Determination of MTBE, ETBE, TAME, DIPE tert-Amyl Alcohol and C1 to C4 Alcohols in Gasoline by Gas Chromatography
D5599 Test Method for Determination of Oxygenates in Gasoline by Gas Chromatography and Oxygen Selective Flame Ionization Detection
3. Terminology
3.1 Definitions:
3.1.1 oxygenate, n - an oxygen-containing organic compound, which may be used as a fuel or fuel supplement, for example, various alcohols and ethers.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 hydrogenation, n - the process of adding hydrogen to olefin molecules as a result of a catalytic reaction.
3.2.1.1 Discussion - Hydrogenation is accomplished when olefins in the sample contact platinum at a temperature of 180°C in the presence of hydrogen. The olefins are converted into hydrogen saturated compounds of the same carbon number and structure. Monoolefins and diolefins convert to paraffins while cycloolefins and cyclodienes convert to cycloparaffins.
3.2.2 trap, n - a device utilized to selectively retain specific portions (individual or groups of hydrocarbons or oxygenates) of the test sample and to release the retained components by changing the trap temperature.
3.3 Acronyms:
3.3.1 ETBE, ethyl-tert-butylether.
3.3.2 MTBE, methyl-tert-butylether.
3.3.3 TAME, tert-amyl-methylether.
