ASTM D2789 Test Method for Hydrocarbon Types in Low Olefinic Gasoline by Mass Spectrometry
1. Scope
1.1 This test method covers the determination by mass spectrometry of the total paraffins, monocycloparaffins, dicycloparaffins, alkylbenzenes, indans or tetralins or both, and naphthalenes in gasoline having an olefin content of less than 3 volume % and a 95 % distillation point of less than 210°C (411°F) as determined in accordance with Test Method D86. Olefins are determined by Test Method D1319, or by Test Method D875.
1.2 It has not beeen determined whether this test method is applicable to gasolines containing oxygenated compounds (for example, alcohols and ethers).
1.3 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 and health practices and determine the applicability of regulatory limitations prior to use.
2. Referenced Documents
2.1 ASTM Standards:
D86 Test Method for Distillation of Petroleum Products
D875 Test Method for Calculation of Olefins and Aromatics in Petroleum Distillates from Bromine Number and Acid Absorption
D1319 Test Method for Hydrocarbon Types in Liquid Petroleum Products by Fluorescent Indicator Adsorption
D2001 Test Method for Depentanization of Gasoline and Naphthas
D2002 Test Methods for Isolation of Representative Saturates Fraction from Low-Olefinic Petroleum Naphthas
3. Terminology
3.1 Definitions of Terms Specific to This Standard:
3.1.1 The summations of characteristic mass fragments are defined as follows:
3.1.1.1 ∑43 (paraffins) = total peak height of m/e(+) 43 + 57 + 71 + 85 + 99.
3.1.1.2 ∑41 (monocycloparaffins) = total peak height of m/e(+) 41 + 55 + 69 + 83 + 97.
3.1.1.3 ∑67 (dicycloparaffins) = total peak height of m/e(+) 67 + 68 + 81 + 82 + 95 + 96.
3.1.1.4 ∑77 (alkylbenzenes) = total peak height of m/e(+) 77 + 78 + 79 + 91 + 92 + 105 + 106 + 119 + 120 + 133 + 134 + 147 + 148 + 161 + 162.
3.1.1.5 ∑103 (indans and tetralins) = total peak height of m/e(+) 103 + 104 + 117 + 118 + 131 + 132 + 145 + 146 + 159 + 160.
3.1.1.6 ∑128 (naphthalenes) = total peak height of m/e(+) 128 + 141 +/- 142 + 155 + 156.
3.1.1.7 T = total ion intensity = ∑41 + ∑43 + ∑67 + ∑77 + ∑103 + ∑128.
3.2 carbon number, by definition, is the average number of carbon atoms in the sample.
3.3 A mass number with a plus sign as superscript is defined as the peak height associated with the same mass number.
