Cas no 67 56 1

A total of six refined petroleum products (Table 1) were used in this study. For evaluation, we selected three products from three broad manufacturing categories of “Solvent naphtha, heavy aromatic products” (marked as AR) and “Petroleum distillates, hydrotreated [light or heavy] paraffinic” (marked as BO). Sample selection was meant to be representative of a wide range of expected chemical complexity of petroleum UVCBs. For each product, samples were obtained from 2–3 independent production cycles at the same refinery (samples were collected 2–3 months apart), resulting in a total of 16 samples (Supplemental Table 1). For GC-MS analyses, samples were weighed and dissolved in dichloromethane (CAS no. 75-09-2, catalog no. 34856; Sigma-Aldrich, St. Louis, MO) to a final concentration of 1 mg/mL. For the IMS-MS analyses, 1 mg of each sample was first dissolved in 9 mL of 1:1 (v/v) mixture of toluene (CAS no. 108-88-3, catalog no. 34866; Sigma-Aldrich) and methanol (CAS no. 67-56-1, catalog no. 34860; Sigma-Aldrich). Next, 25 μL of the solution was mixed with 300 μL of the same mixture of toluene and methanol and injected directly.