“…The literature indicates that reverse phase HPLC has been used for the analysis of diesel, jet fuel, and crude-oil, but group-type separations are most often achieved with normal phase liquid chromatography. , Standard methods, i.e., IP 391, EN-12916, and ASTM D 6591, are available for the group-type separation (based on the number of aromatic rings) of diesel with normal phase HPLC combined with refractive index detection. , Polar silica, aminosilane, or dinitroanilinopropyl-based stationary phases are employed, together with nonpolar solvents (e.g., dichloromethane and hexane) as the mobile phase. The mobile phases employed in normal phase HPLC present two important disadvantages: (i) in terms of health, safety, and environmental impact, these chemicals are classified as “hazardous”, and (ii) ionization suppression is a common phenomenon when normal phase HPLC is hyphenated with electrospray ionization (ESI-MS), and several strategies have been developed to deal with this challenge …”