Gas Chromatography Combined with Mass Spectrometry for the Identification of Organic Sulfur Compounds in Shellfish and Fish

Abstract

The authors determined that the organic sulfur compounds usually contained in crude oil can be used as a marker of oil pollution in shellfish and fish. Short-necked clams (Tapea Angdala phillipinarum A. et Reeve) and eels were maintained in a controlled laboratory environment in water with suspension of crude oil. Mass spectra and mass chromatograms of short-necked clam extract showed the presence of organic sulfur compounds of alkyl- (from C₁ to C ₁₀) benzothlophenes, dibenzothiophene, alkyl- (C₁ to C₈) dibenzothiophene, naphthalene, and alkyl- (C₁ to C₆) naphthalene. Alkyl benzothiophenes and alkyl dibenzothiophenes of low carbon numbers were more easily transferred to short-necked clams than those of higher carbon numbers. Capillary column gas chromatography-mass chromatograms of crude oil and extract from the soft body of a short-necked clam showed the presence of organic sulfur compounds of alkyl benzothiophene (from C₂-C₆), dibenzothiophene, and alkyl dibenzothiophene (C₁-C₄). Besides sulfur components, various other compounds were contained in crude oil and short-necked clam, namely alkyl benzene (C₃-C₉), naphthalene, alkyl naphthalene (C₁-C₅), phenanthrene, alkyl phenanthrene (C₁-C₆), n-paraffin (C₁₂12-C₂₁). and probably pyrene and alkyl pyrene (C₁-C₂). Also, mass chromatograms of crude oil and the extract from eel flesh showed the presence of alkyl benzothlophene (C₁-C₅), dibenzothiophene, naphthalene, and alkyl naphthalene (C₁-C₅). Data indicated that the organic sulfur compounds and poly aromatic compounds could serve as markers of oil pollution in shellfish and fish. For the identification of sulfur compounds by capillary gas chromatography/mass spectrometry, a new intensity matching method was devised.