Analysis of nitroaromatics in aqueous samples by capillary supercritical fluid chromatography

The extraction and analysis of nitroaromatics from aqueous environmental samples was examined. Two extraction methods; liquid-liquid extraction with dichloromethane as extracting solvent and solid phase extraction with C 18 cartridge were carried out to determine the selectivity and extraction efficiencies of each method. In this investigation, eight nitroaromatics were selected as the test compounds. The extracts were then analysed using capillary supercritical fluid chromatography with flame ionization detection and with carbon dioxide as mobile phase. Satisfactory separation of the eight nitroaromatics including three pairs of isomers could be achieved. Detection limits in the range of 5 to 40 ppm were obtained using this system. Higher extraction efficiencies were obtained using the liquid-liquid extraction method compared to the solid phase extraction method.