New benchmark for basic and neutral nitrogen compounds speciation in middle distillates using comprehensive...

Area of Science:

• Analytical Chemistry
• Petroleum Chemistry
• Chromatography

Background:

• Nitrogen compounds in middle distillates pose challenges for analysis due to their diverse types and basicity.
• Accurate quantification of nitrogen compounds is crucial for fuel quality and environmental regulations.

Purpose of the Study:

• To develop and optimize a comprehensive two-dimensional gas chromatography (GCxGC) method for the separation and identification of nitrogen compounds in middle distillates based on basicity.
• To evaluate the impact of different chromatographic conditions and detectors on separation efficiency and sensitivity.

Main Methods:

• Utilized a non-polar x polar GCxGC approach with varying secondary column phases and lengths to optimize separation.
• Investigated the role of permanent dipole-permanent dipole interactions in separating neutral and basic nitrogen compounds.
• Compared two nitrogen chemiluminescence detectors (NCDs) for selective monitoring.

Main Results:

• A polar secondary column with free electron pairs significantly improved the separation of nitrogen compounds.
• The developed GCxGC-NCD method enabled unambiguous identification and quantification of nitrogen compounds by class and carbon number.
• Achieved higher resolution and sensitivity compared to conventional gas chromatography.

Conclusions:

• The optimized GCxGC method provides superior separation and identification of nitrogen compounds in middle distillates.
• The method demonstrates excellent correlation with ASTM standards for determining the basic/neutral nitrogen ratio in diesel samples.
• GCxGC offers significant advantages over conventional methods for analyzing complex petroleum matrices.