Correlation of Total Aromatics and Speciated Aromatic Analysis by ASTM D5769 (Determination of Aromatics) and ASTM D6730 (Detailed Hydrocarbon Analysis) of US Market Gasoline Samples

<div class="section abstract"><div class="htmlview paragraph">The Standard Test Method for Determination of Benzene, Toluene, and Total Aromatics in Finished Gasolines by Gas Chromatography/Mass Spectrometry, also known as ASTM D5769, identifies aromatic compounds ranging from carbon groups six to twelve (C6-C12). This method provides determination in less than 15 minutes of twenty-three target aromatics, quantification of uncalibrated Indans, as well as C10, C11, and C12 aromatics using extracted ions. In contrast, the Standard Test Method for Determination of Individual Components in Spark Ignition Engine Fuels by 100-MetreCapillary (with Precolumn) High-Resolution Gas Chromatography (ASTM D6730) offers a more comprehensive identification of compounds of multiple classes in gasoline samples also using a mass spectrometer (MS), focusing on aromatics from C6 to C14 for this research. This method uses a standard template of identified fuel components and corrects responses based on theoretical Flame Ionized Detector (FID) hydrocarbon responses.</div><div class="htmlview paragraph">The difference in results between these methods in identifying total aromatics and C10+ aromatics has been well documented (Marathon 1998 [<span class="xref">9</span>]). Given the significant contribution of aromatic compounds to particulate emissions indices in spark ignition gasoline, analyzing aromatic content is crucial. The heavier molecular weight aromatics have the largest impact on particulate emissions indices. This study evaluated 40 United States spark ignition market gasoline samples using both ASTM D5769 and ASTM D6730. The results of total and speciated (C6-C14) aromatics will be compared to identify any correlations or differences between the two methods. As a benefit to the industry, any biases that exist between the methods will undergo root cause analysis to determine the source of the bias and how it may impact the quantification and identification of aromatic species.</div></div>