| Abstract: | Series of C-ring monoaromatic steroid hydrocarbons (C21, C22, C27 ? C29) and triaromatic steroid hydrocarbons (C20, C21, C26 ? C28) have been recognized in the aromatic hydrocarbon fraction of Alamein crude oil from the western desert, Egypt. Detection of these compounds were based on mass fragmentography of the key ions m/z 253 and m/z 231 and comparison of the mass spectra and relative retention times with literature data. The predominance of the C29 monoaromatic steroids and C28 triaromatic steroids provide further evidence for a land plant origin of Alamein oil. The results substantiate previous evidence of the occurrence of an aromatization process with increasing maturation and indicate a moderate maturity level for Alamein oil. |
