Infrared and ultraviolet spectrophotometric analysis of chromatographic fractions of crude oils and petroleum products

Samples of light, medium and heavy Nigerian crude oils and petroleum products including diesel oil, engine oil (SAE 40) and gasoline (PMS) have been separated into four fractions of saturates, monoaromatics, diaromatics and polyaromatics by elution liquid chromatography. The fractions obtained were analysed using IR and UV-visible spectrophotometry. The infrared data confirmed the presence of methyl and methylene groups in the saturate fractions of the crude oils and petroleum products. The C=C stretching vibrations and C–H out of plane bending vibration of aromatics were also found in the mono-, di- and polyaromatics fractions. The characteristic UV spectra of alkyl benzenes and naphthalenes were observed in the monoaromatic and diaromatic fractions, respectively. The spectra of the polyaromatic fractions indicate the presence of anthracenes and phenanthrenes. KEY WORDS: Crude oils, Petroleum products, Diesel oil, Engine oil, Gasoline Bull. Chem. Soc. Ethiop. 2007, 21(1), 135-140.