Asphaltenes are a complex and problematic fraction of crude oil that can precipitate, alter wettability and stabilise unwanted oil-in-water emulsions. Asphaltenes have a high proportion of aromatic carbon and heteroatoms (N, S, O) and are generally thought to consist of one (or more) aromatic cores with alkyl side chains. Despite considerable effort, there is little consensus as to the key structural features involved in asphaltene aggregation. We hypothesise that sulfur contining molecules play an important role in promoting aggregation. In the proposed SANDALS experiment we will use neutron diffraction to characterise the liquid structures of sulphur containing molecule (thiophene), and mixtures of thiophene or pyridine with benzene. The measurements will have particular significance for the study of the structure in biological macro-molecules and crude oil asphaltenes.