Determination of N-Alkane and Methylnaphthalene Compounds in Shellfish

During the course of investigations to determine the possible toxicity of petroleum to marine biota, it became evident that quantitative estimates of the petroleum components in water and biota would assist in meaningful interpretation of the results of bioassays. However, published procedures for estimation of n-alkanes in marine biota were largely qualitative, and even less effort had been afforded the measurement of aromatic petroleum residues. A method originally utilized for determination of poly cyclic aromatic hydrocarbons in foods was therefore adapted for the digestion of tissue and extraction of hydrocarbons from shellfish exposed to petroleum during bioassays. Tissue extracts were partitioned into saturate and aromatic fractions by column chromatography. Using gas-liquid chromatography, the n-alkanes of carbon numbers 12 to 19, and the methyl substituted naphthalenes were identified in the saturate and aromatic fractions, respectively. Both groups of compounds were quantitated by reference to an internal standard.

The procedure allowed recovery of over 70 percent of n-alkanes and methylnaphthalenes applied to the tissues prior to digestion. Minimum detectable levels for n-alkanes and methylnaphthalenes were approximately 0.08 to 0.15 and 0.03 to 0.04 µg/g of wet tissue, respectively.