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A round robin study to measure the aromatic levels in diesel fuels was conducted by the Chemical Characterization Panel of the Coordinating Research Council Air Pollution Research. Advisory Committee (CRC-APRAC) In-house Program Group, CAPI-1-64. The fuels for this study consisted of a jet fuel, a No. 2 diesel reference fuel, and three fuels used in a CRC-sponsored diesel emission project (CAPE-32) These fuels had 90% distillation temperatures which ranged from 472° to 642° F and aromaticity levels from approximately 18 to 55% by volume. All participants used the American Society for Testing and Materials (ASTM) D1319 or modified D1319 methods to measure the aromatic levels in the selected fuels. Some participants concurrently analyzed the same fuels using other methods such as high-performance liquid chromatography, mass spectrometry, nuclear magnetic resonance spectrometry, and elution chromatography (ASTM D2549).

The effects of fuel composition on diesel exhaust particulate emissions have been studied at several steady-state operating conditions using a heavy-duty laboratory engine. Particulate emissions were influenced by three primary fuel factors: sulfur content, aromatics content, and volatility. At all but lightly loaded operating conditions, fuel sulfur was the dominant fuel factor in particulate formation. Fuel sulfur affects particulate emissions primarily by formation of sulfate (as sulfuric acid) and associated “bound” water and, to a lesser degree, by increasing the amount of soluble organic material collected. Aromatics and volatility influence the amount of carbonaceous material formed. Five polynuclear aromatic hydrocarbon (PAH) compounds were measured in the soluble organic fraction. Engine operating conditions greatly affected PAH levels; however, no strong influence of fuel composition on PAH concentrations was observed in the normal range of No. 1 - No. 2 diesel fuels.