Research on Traceability of SBr Interference to Gasoline Identification Based on Pyrolysis Mechanism and Chemical Structure

Matrix interference remains a key issue in gasoline identification. Our previous research has demonstrated that styrene-butadiene rubbers (SBrs) can cause remarkable interference with gasoline identification, with the extent of this interference being highly dependent on the chemical structure of the SBrs. To trace the origins of the interference, the pyrolysis mechanism of SBrs with varying butadiene concentration was inferred based on results concerning pyrolysis products and thermal stability, and factors of the pyrolysis mechanism and chemical structure of the SBrs were involved together to explain the chemical-structure-dependent matrix interference extent reported previously. The results indicated that the total amount of butadiene in SBrs was a key point for causing interference with gasoline identification. The pyrolysis products of SBr 1205 with the highest butadiene concentration were long-chain straight alkenes of varying lengths. Meanwhile, SBr 1205 exclusively possessed cis-structure, resulting in the majority of its pyrolysis products being cis-structures, which were speculated to be precursors to form aromatic compounds by cyclization during combustion. The study revealed that the chain-structured cis-alkenes with varying lengths generated during pyrolysis played an important role in causing remarkable interference with gasoline identification, which provided valuable insights for understanding and predicting the matrix interference for fire debris analysis.