ASTM D6550-20

5.1 Gasoline-range olefinic hydrocarbons have been demonstrated to contribute to photochemical reactions in the atmosphere, which result in the formation of photochemical smog in susceptible urban areas.

5.2 The California Air Resources Board (CARB) has specified a maximum allowable limit of total olefins in motor gasoline. This necessitates an appropriate analytical test method for determination of total olefins to be used both by regulators and producers.

5.3 This test method compares favorably with Test Method D1319 (FIA) for the determination of total olefins in motor gasolines. It does not require any sample preparation, has a comparatively short analysis time of about 10 min, and is readily automated. Alternative methods for determination of olefins in gasoline include Test Methods D6839 and D6296.

1.1 This test method covers the determination of the total amount of olefins in blended motor gasolines and gasoline blending stocks by supercritical-fluid chromatography (SFC). Results are expressed in terms of mass percent olefins. The method working range is from expected concentration of 1 % by mass to expected concentration of 25 % by mass total olefins.

1.2 This test method can be used for analysis of commercial gasolines, including those containing varying levels of oxygenates, such as methyl tert/butyl ether (MTBE), diisopropyl ether (DIPE), methyl tert/amyl ether (TAME), and ethanol, without interference.

1.3 This test method includes a relative bias section based on Practice D6708 accuracy assessment between Test Method D6550 mass percent and Test Method D1319 volume percent for total olefins in spark-ignition engine fuels as a possible Test Method D6550 alternative to Test Method D1319 for U.S. EPA regulations reporting. The Practice D6708 derived correlation equation is only applicable for test result range from 0.53 % to 26.88 % by mass as reported by Test Method D6550.

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

1.5 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.

1.6 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.