Identification of N ‐methylaniline in automotive gasoline by GC‐MS , MS / MS , and ATR ‐ FTIR : A report of fuel adulteration

This case study reports the forensic identification of N-methylaniline (NMA) in an automotive gasoline sample seized from a gas station in Brazil, with a semi-quantitative estimate of ca. 1.9% (v/v), indicating a case of fuel adulteration. Although NMA has been investigated in experimental fuel formulations as a potential nonmetallic anti-knock additive capable of increasing octane rating, to the best available knowledge, no previous studies have reported its detection in real-world gasoline samples. In Brazil, the National Petroleum Agency (ANP) authorizes only previously approved additives, meaning that the presence of NMA constitutes a noncompliant fuel component. The sample was analyzed using gas chromatography-mass spectrometry (GC-MS), tandem mass spectrometry (MS/MS), and attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR). The compound was unambiguously identified and characterized, demonstrating the effectiveness of these complementary analytical techniques for detecting unapproved or unconventional additives in complex hydrocarbon matrices. This case underscores the relevance of forensic fuel analysis for regulatory compliance and highlights the need for continuous monitoring to mitigate health, environmental, and operational risks associated with aromatic amine contamination.