ASTM D7096 Standard Test Method for Determination of the Boiling Range Distribution of Gasoline by Wide-Bore Capillary Gas Chromatography
15. Report
15.1 Boiling range distribution may be reported in two formats: boiling temperature as a function of volume percent distilled or volume percent distilled as a function of boiling temperature. The former is in a format similar to conventional (pot) distillations, while the latter presents data useful for gasoline blending applications. Calculations and reporting may be conducted in either Fahrenheit (°F) or Celsius (°C). Precision data was determined in degrees Celsius (see X2.1).
15.1.1 Boiling Temperature at 1 Vol% Increments (Distillation Format) - Search the table of cumulative volume percents (see 14.6) for the first occurrence of a volume percent equal to or greater than 0.5 %. Report the boiling temperature (to the nearest (0.5 °C or 1 °F)) associated with this percent as the IBP. Repeat for each increment from 1 % through 99 %, and for 99.5 % (FBP).
15.1.2 Volume Percent at 10° Increment Intervals (°C or °F) (Blending Format) - Search the table of cumulative volume percents (see 14.6) for the first occurrence of a boiling temperature equal to or greater than 0° (°C or °F). Report the cumulative volume percent (to the nearest 0.1 %) associated with that temperature as the volume percent distilled through 0° (°C or °F). Repeat for each subsequent 10° increment to cover the selected interval.
15.2 If desired, report the estimated volume percent of propane, isobutane, butane, isopentane, and pentane individually. This provides a more detailed description of the volatile components in gasoline. Propylene, butenes, and some pentenes will coelute with the above-mentioned compounds.
15.2.1 The volume percent propane is arbitrarily defined as the cumulative volume percent through a slice time half way between the propane and isobutane retention times.
15.2.2 The volume percent isobutane is determined by subtracting the volume percent propane from the cumulative volume percent through a slice time half way between the isobutane and n-butane retention times.
15.2.3 The volume percent n-butane is determined by subtracting the volume percents ofpropane and isobutane from the cumulative volume percent through a slice time half way between the n-butane and isopentane retention times.
15.2.4 The volume percent of isopentane is determined as follows:
15.2.4.1 For gasolines not containing ethanol, the volume percent isopentane is determined by subtracting the volume percents of propane, isobutane, and n-butane from the cumulative volume percent through a slice time halfway between the isopentane and n-pentane retention times.
15.2.4.2 For gasolines containing ethanol, the volume percent of isopentane is determined by subtracting the volume percents of propane, isobutane, n-butane and ethanol from the cumulative volume percent through a slice time half way between the isopentane and n-pentane retention times.
15.2.5 The volume percent of n-pentane is determined as follows:
15.2.5.1 For gasolines not containing ethanol, the volume percent n-pentane is determined by subtracting the volume percent propane, isobutane, n-butane, and isopentane from the cumulative volume percent through a slice time half way between the n-pentane and 2-methylpentane retention times.
15.2.5.2 For gasolines containing ethanol, the volume percent of n-pentane is determined by subtracting the volume percents of propane, isobutane, n-butane and ethanol from the cumulative volume percent through a slice time half way between the isopentane and n-pentane retention times.
NOTE 4 - Some commercial simulated distillation software reports the slice width, total area, and retention time corresponding to the end of sample for diagnostic purposes.
NOTE 5 - When reporting data, identify that the boiling point distribution is calculated by this test method. This is recommended to distinguish the data from that of other distillation methods.
16. Precision and Bias
16.1 The precision of this test method was determined by the statistical examination of the interlaboratory test results for finished gasoline, alkylate, reformate, heavy naphtha, and gasoline with up to 10 volume % ethanol. Boiling point ranges covered in the interlaboratory study are shown in Table 6). Precision is as follows:
16.1.1 Repeatability - The difference between successive test results obtained by the same operator with the same apparatus under constant operating conditions on identical test material would, in the long run, in the normal and correct operation of the test method, exceed the values shown in Table 7 for boiling point distribution and Table 8 for the estimated gas concentrations in only one case in twenty.
16.1.2 Reproducibility - The difference between two single and independent test results obtained by different operators working in different laboratories on identical test material would, in the long run, in the normal and correct operation of the test method, exceed the values shown in Table 7 for BP distributions and Table 8 for the estimated gas concentrations in only one case in twenty.
16.2 Bias - The bias in results of this test method cannot be determined because the boiling range distribution is defined by the test method.
NOTE 6 - The precision statement is reported in RR:D02-1682. It was carried out by eleven participants with ten samples which included ethanol containing gasolines. It is to be noted that the required degrees of freedom (Q>P) according to 6.4.3 (Note 1) of Practice D6300, recommended "further standardization of the test method may be necessary".
17. Keywords
17.1 blending streams; boiling range distribution; capillary gas chromatography; gas chromatography; gasoline; oxygenate
