Abstract: The method for the separation and determination of nitrogen compounds in catalytic diesel oil using gas chromatography-nitrogen chemiluminescence detection (GC-NCD) was established. The effects of the flow rate of carrier gas and oven temperature on the resolution were studied. More than 80 nitrogen compounds (such as aniline, alkyl anilines, quinoline, indole, alkyl indoles, carbazole, alkyl carbazoles) in catalytic diesel oil were enriched using an Al2O3 column and identified based on the retention time of some pure nitrogen compounds and the retention index of nitrogen compounds on GC-NCD. The relative standard deviations of the peak areas of main nitrogen compounds in catalytic diesel oil were lower than 8%. The detection limit (S/N=3) for nitrogen of carbzole was 1.0 mg/L under the chosen conditions. The linear range of nitrogen was 1.0-600 mg/L for each nitrogen compound. The correlation coefficient was more than 0.998. The recoveries of four nitrogen compounds (aniline, quinoline, indole, carbazole) in catalytic diesel oil were in the range of 89.5%-99.8%. The method can be applied for the determination of each nitrogen compound in different catalytic diesel oils.

Key words: diesel oil , distribution of nitrogen compounds, gas chromatography-mass spectrometry (GC-MS), gas chromatography-nitrogen chemiluminescence detection (GC-NCD)