ASTM - D6839
Standard Test Method for Hydrocarbon Types, Oxygenated Compounds, and Benzene in Spark Ignition Engine Fuels by Gas Chromatography
|Publication Date:||1 April 2018|
|ICS Code (Chemical analysis):||71.040.40|
This test method covers the quantitative determination of saturates, olefins, aromatics, and oxygenates in sparkignition engine fuels by multidimensional gas chromatography. Each hydrocarbon type can be reported either by carbon number (see Note 1) or as a total.
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.
This test method is not intended to determine individual hydrocarbon components except benzene.
This test method is divided into two parts, Part A and Part B.
Part A is applicable to automotive motor gasoline for which precision (Table 9) has been obtained for total volume fraction of aromatics of up to 50 %; a total volume fraction of olefins from about 1.5 % up to 30 %; a volume fraction of oxygenates, from 0.8 % up to 15 %; a total mass fraction of oxygen from about 1.5 % to about 3.7 %; and a volume fraction of benzene of up to 2 %. Although this test method can be used to determine higher-olefin contents of up to 50 % volume fraction, the precision for olefins was tested only in the range from about 1.5 % volume fraction to about 30 % volume fraction. The method has also been tested for an ether content up to 22 % volume fraction but no precision data has been determined.
This test method is specifically developed for the analysis of automotive motor gasoline that contains oxygenates, but it also applies to other hydrocarbon streams having similar boiling ranges, such as naphthas and reformates.
Part B describes the procedure for the analysis of oxygenated groups (ethanol, methanol, ethers, C3 to C5 alcohols) in ethanol fuels containing an ethanol volume fraction between 50 % and 85 % (17 % to 29 % oxygen). The gasoline is diluted with an oxygenate-free component to lower the ethanol content to a value below 20 % before the analysis by GC. The diluting solvent should not be considered in the integration, this makes it possible to report the results of the undiluted sample after normalization to 100 %.
Oxygenates as specified in Test Method D4815 have been verified not to interfere with hydrocarbons. Within the round robin sample set, the following oxygenates have been tested: MTBE, ethanol, ETBE, TAME, iso-propanol, isobutanol, tert-butanol and methanol. The derived precision data for methanol do not comply with the precision calculation as presented in this International Standard. Applicability of this test method has also been verified for the determination of n-propanol, acetone, and di-isopropyl ether (DIPE). However, no precision data have been determined for these compounds.
Other oxygenates can be determined and quantified using Test Method D4815 or D5599.
The method is harmonized with ISO 22854.
This test method includes a relative bias section for U.S. EPA spark-ignition engine fuel regulations for total olefins reporting based on Practice D6708 accuracy assessment between Test Method D6839 and Test Method D1319 as a possible Test Method D6839 alternative to Test Method D1319. The Practice D6708 derived correlation equation is only applicable for fuels in the total olefins concentration range from 0.2 % to 18.2 % by volume as measured by Test Method D6839. The applicable Test Method D1319 range for total olefins is from 0.6 % to 20.6 % by volume as reported by Test Method D1319.
The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
*A Summary of Changes section appears at the end of this standard