Effective methods of analyzing the relationships between diesel fuel properties and particulate ( PM ) emissions were examined. First, the entire compositions of hydrocarbons in a diesel fuel were clarified by using their molecular formulas. Based on this clarification, the analytical methods which efficiently characterize diesel fuels were then examined. It was found that a combination of gas chromatography to separate hydrocarbons by boiling point and high-presssure liquid chromatography to separate them by polarity was most effective and efficient for characterizing hydrocarbons of many kinds of diesel fuels. The other fuel properties were also considered from the viewpoint of the PM formation mechanism. �@
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