NH2-SEP-PAK cartridges for enrichment of Aromatic Sulfur Compounds from sea water: determination by GC-FID and GC-MS

The Aromatic Sulfur Compounds (ASCs) are considered as "markers" of the crude oil age. In this frame, we have considered ASCs as "markers" of remote crude oil sea water pollution for their chemical characteristics, good solubility in water and resistance to the biodegradation. Gas chromatography of ASCs in distilled water and sea water samples has been performed after adsorption from a 80 mL water sample on to a cartridge containing 100 mg NH2-bonded porous silica. The ASCs are desorbed with 2 mL acetone-trichloromethane (1:1), which is concentrated and analysed by GC-FID or GC-MS in SIM mode. The average recovery of 0.1 microg mL(-1) of each ASC from distilled water and 0.04-0.2 microg mL(-1) from sea water samples is > or = 96.3% with a standard deviation < or = 2.2. The limits of detection are 0.06-0.05 ng mL(-1) for thiophen-2-carboxaldehyde and benzothiophene, and 0.006-0.004 ng mL(-1) for dibenzothiophene and thiantrene in GC-FID whereas they are 0.02 ng mL(-1) for thiophen-2-carboxaldehyde and benzothiophene, and 0.003 ng mL(-1) for dibenzothiophene and thiantrene in GC-MS (SIM) with a relative standard deviation < or =7.