Significance and Use
5.1 This test method provides a method of determining the percentage of ethanol in an ethanol-gasoline fuel blend over the range of 20 % by  mass to 100 % by mass for compliance with fuel specifications and federal or local fuel regulations.
5.2 Ethanol content of denatured fuel ethanol for gasoline blending is required in accordance with Specification D4806.
5.3 Ethanol content of ethanol fuel blends for flexible-fuel automotive spark-ignition engines is required in accordance with Specification D5798.
5.4 This test method is acceptable for determining the percentage of ethanol for either denatured fuel ethanol or undenatured ethanol for use in industrial applications using Table 3(a) or Table 3(b).
5.4.1 Refer to local, federal, or other authorities having jurisdiction for information regarding the correct implementation of either Table 3(a) or Table 3(b).
5.4.2 Specific regulatory requirements for U.S. domestic fuel applications are given in Appendix X5 for information.
Scope
1.1 This test method covers the determination of the ethanol content of hydrocarbon blends containing greater than 20 % ethanol. This method is applicable to denatured fuel ethanol, ethanol fuel blends, and mid-level ethanol blends.
1.1.1 Ethanol is determined from 20 % by mass to 100 % by mass and methanol is determined from 0.01 % by mass to 0.6 % by mass. Equations used to convert these individual alcohols from percent by mass to percent by volume are provided.
Note 1: Fuels containing less than 20 % ethanol may be quantified using Test Method D5599, and less than 12 % ethanol may be quantified using Test Method D4815.
1.2 This test method does not purport to identify all individual components common to ethanol production or those components that make up the denaturant or hydrocarbon constituent of the fuel.
1.3 Water cannot be determined by this test method and shall be measured by a procedure such as Test Method D7923, E203, or E1064 and the result used to correct the concentrations determined by this method.
1.4 This test method is inappropriate for impurities that boil at temperatures higher than 225 °C or for impurities that cause poor or no response in a flame ionization detector, such as water.
1.5 The values stated in SI units are to be regarded as the standard. The values given in parentheses are provided for information purposes only.
1.6 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.
1.7 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.
