This document specifies the gas chromatographic (GC) method for the determination of saturated, olefinic and aromatic hydrocarbons in automotive motor gasoline and ethanol (E85) automotive fuel. Additionally, the benzene and toluene content, oxygenated compounds and the total oxygen content can be determined.
NOTE 1 For the purposes of this document, the terms % (m/m) and % (V/V) are used to represent respectively the mass fraction, w, and the volume fraction, φ.
This document defines two procedures, A and B.
Procedure A is applicable to automotive motor gasoline with total aromatics of 19,32 % (V/V) up to 46,29 % (V/V); total olefins from 0,40 % (V/V) up to 26,85 % (V/V); oxygenates from 0,61 % (V/V) up to 9,85 % (V/V); oxygen content from 1,50 % (m/m) to 12,32 % (m/m); benzene content from 0,38 % (V/V) up to 1,98 % (V/V) and toluene content from 5,85 % (V/V) up to 31,65 % (V/V).
The method has also been tested for individual oxygenates. A precision has been determined for a total volume of methanol from 1,05 % (V/V) up to 16,96 % (V/V); a total volume of ethanol from 0,50 % (V/V) up to 17,86 % (V/V); a total volume of MTBE from 0,99 % (V/V) up to 15,70 % (V/V), a total volume of ETBE from 0,99 % (V/V) up to 15,49 % (V/V), a total volume of TAME from 0,99 % (V/V) up to 5,92 % (V/V), and a total volume of TAEE from 0,98 % (V/V) up to 15,59 % (V/V).
Although this test method can be used to determine higher-olefin contents of up to 50 % (V/V), the precision for olefins was tested only in the range from 0,40 % (V/V) to 26,85 % (V/V).
Although specifically developed for the analysis of automotive motor gasoline that contains oxygenates, this test method can also be applied to other hydrocarbon streams having similar boiling ranges, such as naphthas and reformates.
NOTE 2 For Procedure A, applicability of this document 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.
Procedure B describes the analysis of oxygenated groups (ethanol, methanol, ethers, C3 – C5 alcohols) in ethanol (E85) automotive fuel containing ethanol between 50 % (V/V) and 85 % (V/V). The gasoline is diluted with an oxygenate-free component to lower the ethanol content to a value below 20 % (V/V) before the analysis by GC.
The sample can be fully analysed including hydrocarbons. Precision data for the diluted sample are only available for the oxygenated groups.
NOTE 3 For Procedure B, the precision can be used for an ethanol fraction from about 50 % up to 85 % (V/V). For the ether fraction, the precision as specified in Table 6 can be used for samples containing at least 11 % (V/V) of ethers. For the higher alcohol fraction, too few data were obtained to derive a full precision statement and the data presented in Table 6 are therefore only indicative.
NOTE 4 An overlap between C9 and C10 aromatics can occur. However, the total is accurate. Isopropyl benzene is resolved from the C8 aromatics and is included with the other C9 aromatics.