Liquid Chromatographic Separation and FT-ICR MS of Crude Oils: Insights from Polar Fractions

Molecular characterization of petroleum and reservoir fluids is fundamental to the oil exploration and production sector. However, the complexity of the sample has been an analytical challenge, requiring modern analysis techniques such as ultrahigh-resolution mass spectrometry techniques integrated with chromatographic separation systems. The focus of this study was the detailed molecular characterization of the polar fraction of crude oils, supported by chromatographic fractionation to improve class identification and support geochemical interpretation. Chromatographic fractionations were conducted using H-MPLC, followed by characterization using ESI (±) and APPI (+) FT-ICR MS. Polar compounds from ten Brazilian crude oils were separated into six fractions (low polarity-LP, low medium polarity-LMP, high medium polarity-HMP, high polarity-HP, basic-BAS, acidic-ACD). Molecular profiles through ESI (±) and APPI (+) FT-ICR-MS allowed for the characterization of geochemical processes, formation mechanisms, and the discrimination of oils based on their origin classification and thermal evolution.