--- title: "ASTM D2650" url: "https://mat-cs.com/astm-d2650/" description: "This test method covers the quantitative analysis of gases containing specific combinations of the following components: hydrogen; hydrocarbons with up to six carbon atoms per molecule; carbon monoxide; carbon dioxide; mercaptans with one or two carbon atoms per molecule; hydrogen sulfide; and air (nitrogen, oxygen, and argon). This test method cannot be used for the determination of constituents present in amounts less than 0.1 mole %. Dimethylbutanes are assumed absent unless specifically sought." --- ASTM Standard # ASTM D2650 Standard Test Method for Chemical Composition of Gases by Mass Spectrometry [Back to all techniques](/analytical-techniques/) ## Significance and Use 5.1 A knowledge of the composition of refinery gases is useful in diagnosing the source of plant upsets, in determining the suitability of certain gas streams for use as fuel, or as feedstocks for polymerization and alkylation, and for monitoring the quality of commercial gases. ## Scope 1.1 This test method covers the quantitative analysis of gases containing specific combinations of the following components: hydrogen; hydrocarbons with up to six carbon atoms per molecule; carbon monoxide; carbon dioxide; mercaptans with one or two carbon atoms per molecule; hydrogen sulfide; and air (nitrogen, oxygen, and argon). This test method cannot be used for the determination of constituents present in amounts less than 0.1 mole %. Dimethylbutanes are assumed absent unless specifically sought. Note 1: Although experimental procedures described herein are uniform, calculation procedures vary with application. The following influences guide the selection of a particular calculation: qualitative mixture composition; minimum error due to components presumed absent; minimum cross interference between known components; maximum sensitivity to known components; low frequency and complexity of calibration; and type of computing machinery. Because of these influences, a tabulation of calculation procedures recommended for stated applications is presented in Section 12 (Table 1). Serial No. . . . . . . . . . . 7 8 9 10 11 12 13 Name or Application Commercial Propane Commercial Butane BB Stream (Cracked Butanes) Dry Gas Cracked Fuel Gas Mixed Iso and Normal Butanes Reformer Make-Up Gas Unstabi- lized Fuel Gas — — — — — — — — Component O P M O P M OC Hydrogen … … … … … … … Methane … … … … … … … EthyleneE 7 26 M … … … … Ethane 6 30 M … … … … Propene 5 42 M 7 42 M 6 Propane 3 44 M 4 44 M 4 Butadiene … … … … … … 1 Butene-1 1 56 M 1 56 M 7 Butene-2 1 56 M 1 56 M 8 Isobutene 1F F M 1 F F 9 Isobutane 4 43 M 5 43 M 5 _n_\-Butane 2 58 M 2 58 M 2 Pentenes … … … 6 70 M G Isopentane … … … 3 57 M 3 _n_\-Pentane … … … … … … … Benzene … … … … … … … Hexanes … … … … … … … C6 cyclic paraffins … … … … … … … Hexanes … … … … … … … Toluene … … … … … … … Hydrogen sulfide … … … … … … … Carbon dioxide … … … … … … … Carbon monoxide … … … … … … … Nitrogen … … … … … … … Air … … … … … … … Acid Gases … … … … … … … ResidualE 8 27 M 8 27 M 10 ResidualE 9 29 M 9 29 M 11 ResidualE … … … … … … … ResidualE … … … … … … … Serial No. . . . . . . . . . . 14 15 16 Name or Application H2-C6 Cracked Gas H2-C6 Straight Run Gas Light Refinery Gas — — — — Component O P M Hydrogen 1 2 M Methane 2 16 M Ethylene 4 26 M Ethane 7 30 M Propene 11 42 M Propane 6 29 M Butadiene 15 54 M Butane-1 … … … Butene-2 16 56 M Isobutene … … … Isobutane 12 43 M _n_\-Butane 18 58 M Pentenes 21 70 M Isopentane 17 57 M _n_\-Pentane 22 72 M Benzene … … … Hexanes 23 84 M C6 cyclic paraffins … … … Hexanes … … … Toluene … … … Hydrogen sulfide 9 34 M Carbon dioxide 13 44 M Carbon monoxide … … … Nitrogen 5 28 M Air 8 32 M Water 3 18 M Cyclobutane … … … Cyclopentene 20 67 M Pentadienes 20 67 M Cyclopentane … … … Methylmercaptan 14 48 M Ethylmercaptan 19 62 M Residual 41 10 41 M Residual 14 24 14 M Note 2: This test method was developed on Consolidated Electrodynamics Corporation Type 103 Mass Spectrometers. Users of other instruments may have to modify operating parameters and the calibration procedure. 1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.