Gas Chromatography Method for Identifying Individual Components in Spark Ignition Engine Fuels ASTM D6623

High-Resolution Gas Chromatography Method for Identifying Individual Components in Spark Ignition Engine Fuels in accordance with ASTM D6623

Test method overview

This standard, designated as ASTM D 6623, outlines the year it was originally adopted or last revised, with a parenthetical indicating the most recent reapproval year. Editorial changes since the last revision are marked by a superscript epsilon (ε).

Introduction

This test method introduces three distinct procedures—A, B, and C—for analyzing spark ignition engine fuels. Procedure A, known as Detailed Hydrocarbon Analysis (DHA), set the foundation for ASTM development. Procedure B, or Individual Hydrocarbon Analysis (IHA), adapts from the Canadian CAN/CGSB-3.0 No. 14-3-94, whereas Procedure C aligns with the French Standard NF M07-086. Procedures A and B utilize 100-meter poly(dimethyl)siloxane capillary columns, contrasting with Procedure C's 50-meter column. Procedure A uniquely incorporates a precolumn to enhance separation selectivity. Precision statements for each method derive from similar samples for A and B, with a distinct set for C, all underpinned by ASTM's approved statistical methods. Despite shared equipment and gas chromatography practices, the test delineates each procedure's specific requirements, system optimization, calibration, and precision details. Users are urged to specify the procedure used when sharing or comparing results. Appendix X1 compares data from Procedures A and B against other methods for certain oxygenates and hydrocarbon types, noting that Procedure C's comparison data remains unprovided due to different sample sets used.

1. Scope

1.1 Procedures A and B:

1.1.1 These procedures identify individual hydrocarbons and oxygenate blends (e.g., MTBE, ETBE, ethanol) in spark-ignition engine fuels up to a 225°C boiling range. They are also applicable to other petroleum refining mixtures like naphthas, albeit primarily validated for blended engine fuels.

1.1.2 Precision and component concentration range from 0.01 to around 30% mass percent, based on cooperative study results. Users should verify accuracy for concentrations outside these ranges.

1.1.3 Specifically, Procedures A and B measure methanol, ethanol, t-butanol, MTBE, ETBE, and TAME within a 1 to 30 mass% range, with statistical backing particularly for MTBE in Procedure B.

1.1.4 Some compound co-elution occurs. If using this method for PONA group-type estimation, users should be aware of potential inaccuracies due to co-elution and unidentified components. Particularly, virgin naphthas and other samples with high olefinic or naphthenic content may introduce errors in PONA groupings.

1.1.5 For water presence, Test Method D 1744 or equivalents are recommended. Other specific compounds, if present, should be identified using respective standardized methods.

1.2 Procedure C:

1.2.1 Focused on spark-ignition engine fuels up to a 225°C boiling range, Procedure C is suitable for various petroleum blends, with precision derived from spark-ignition fuel analyses.

1.2.2 This method also applies to oxygenate-containing fuel blends, with oxygenate content determination advised through Test Methods D 5599 or D 4815.

1.2.3 to 1.2.5 highlight the treatment of benzene and toluene co-elution issues, and the potential inaccuracies in PONA estimations due to co-elution and unidentified components. Olefins concentration applicability is noted up to 20 mass %.

1.2.6 Suggests Test Method D 1744 for water concentration determination and emphasizes the need for specific methods to identify other non-hydrocarbon compounds present.

1.3 States SI units as the standard, providing non-SI units for informational purposes only.

1.4 Advises on the necessity for appropriate safety and health practices and compliance with regulatory limitations.

This comprehensive guide offers detailed methodologies for accurately determining the composition of spark ignition engine fuels, crucial for quality control and regulatory compliance within the petroleum industry.