Nitrogen speciation of polar petroleum compounds by compound class separation and on‐line liquid chromatography – mass spectrometry (LC‐MS)

Chromatography on Attapulgus clay and on silicic acid has been used to isolate ‘neutral’ and ‘basic’ nitrogen fractions from the 650–1050 °F distillate of an off‐shore Californian crude oil. These polar compounds were subjected to on‐line liquid chromatography – mass spectrometric (LC‐MS) analysis using low voltage electron‐impact ionization high resolution mass spectrometry (LVEI HRMS) and deuterated ammonia chemical ionization (ND 3 Cl) to determine the molecules' elemental composition and number of exchangeable hydrogen atoms. On‐line separation of heavy oils into saturated, 1–4 ring aromatic, and polar compounds was performed by normal phase high performance liquid chromatography (HPLC) on a dinitroanilinopropyl (DNAP) silica column.