This study is aimed to extend an application of the differential scanning calorimeter (DSC) based vapor pressure method to evaluate vaporization of a target substance from a complex matrix that exhibits several times lower vapor pressure. The experiments involved preparing mixtures of known composition and measuring their vapor pressure by a DSC based vapor pressure method (following ASTM 1785 guidelines). The vapor pressure of two types of associating "binary systems" were examined: (1) a narrow boiling range oil fraction (or distillation cut) mixed with a pure compound (nicotine or 2-tert-butylphenol); (2) a mixture of two narrow boiling range oil fractions. Emphasis was placed on 50:50 mol% mixtures. To evaluate deviation from ideality, the total vapor pressure curves measured were compared to values calculated from Raoult's law. Narrow boiling range oil fractions (distillation cuts) were treated as single pseudocomponents in these calculations. The vapor pressure curves obtained suggest that the DSC based vapor pressure method is a useful tool for characterizing these kinds of multicomponent systems. The results presented can be viewed as a preliminary indication of the extent of ideality in systems containing "synthetic crude oil" from Kukersite oil shale, which is rich in alkyl-phenolic moieties. (C) 2016 Elsevier B.V. All rights reserved.