October 11, 2018 @ 10:00 am – 11:00 am

ASTM D8071 uses gas chromatography – vacuum ultraviolet spectroscopy (GC-VUV) to determine paraffins, isoparaffins, olefins, naphthenes, and aromatics (PIONA), as well as select hydrocarbons and methanol and ethanol, in gasoline.  Run times are less than 35 min followed by automated data processing.  Benzene, toluene, ethylbenzene, xylenes, isooctane, naphthalene, and methylnaphthalenes are accurately quantified as individual categories due to their unique VUV absorbance spectra, even if they coelute with other compounds in the short analysis time.

While ASTM D8071 is defined as a “bulk composition” method for automotive spark-ignition fuels, additional specific compounds and compound classes are easily quantified using the same GC conditions if their VUV absorbance spectra allow them to be distinguished from potential interferences.  One example is diolefin determination, including conjugated diolefins that cause fuel stability problems.  Another application is monitoring for non-traditional gasoline additives (NTGAs).  NTGAs researched as octane boosters, e.g., methyl and ethyl acetates, and more exotic bio-derived oxygenates like ethyl levulinate and gamma-valerolactone, and even potentially harmful NTGAs like acetone and N-Methylaniline, are easily analyzed using the GC-VUV conditions employed for ASTM D8071.  Legacy methods like ASTM D6730, Detailed Hydrocarbon Analysis (FID), are not easy to adapt for diolefins and NTGAs, since they rely on GC with a non-specific flame ionization detector (FID).

This presentation will review the current scope of ASTM D8071, Determination of Hydrocarbon Group Types and Select Hydrocarbon and Oxygenate Compounds in Automotive Spark-Ignition Engine Fuel Using Gas Chromatography with Vacuum Ultraviolet Absorption Spectroscopy Detection (GC-VUV), and show how the same method conditions can be used to quantify additional compounds of interest.

Key Learning objectives

  • Introduction to vacuum ultraviolet spectroscopy as a gas chromatography detector for volatile petroleum hydrocarbons.
  • Fast 33.5-minute determination of paraffins, isoparaffins, olefins, naphthenes, aromatics (PIONA), and select hydrocarbons and oxygenates, in gasolines using gas chromatography – vacuum ultraviolet spectroscopy (GC-VUV) with ASTM D8071.
  • Quantitative analysis of conjugated diolefins in gasoline-range samples using the same fast GC-VUV conditions specified in ASTM D8071.
  • Quantitative analysis of harmful and beneficial non-traditional gasoline additives using the same fast GC-VUV conditions specified in ASTM D8071.
  • The power of VUV spectral identification and deconvolution, and automated data processing, for producing accurate results for gasoline-range sample analysis.

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