The properties of nitrogen compounds are a subject of interest to petroleum refiners due to the detrimental role, these compounds play in catalyst deactivation and product stability. It is thought that basic nitrogen is a major contributor to these phenomena, and therefore identification and quantification of nitrogen species by type would be of great importance. A practical miniaturized method for quantitative separation of nitrogen compounds by type in petroleum distillates is described. Solid phase extraction methodology was used to concentrate the nitrogen compounds and to separate them further into neutral and basic types. The basic nitrogen compounds could not be fully recovered, while full recovery was achieved for the neutral nitrogen types. The amount of basic nitrogen was calculated by difference, and boiling point distribution profiles were produced. For identification of nitrogen compounds in separated fractions, a combined GC-MS/AED method with retention time locking was used. Carbazole and its substituted derivatives methyl, dimethyl, and trimethylcarbazoles were identified in the product from fluid catalytic cracking. Crown Copyright (C) 2003 Published by Elsevier Science Ltd. All rights reserved.