Plastic antioxidants: A family of cocaine cutting agents analyzed by short column gas chromatography-mass spectrometry.

Plastic antioxidants (PAOs), which are used in the industry to prevent degradation caused by thermo-mechanical or thermo-oxidative conditions, have been found in cocaine products seized by the Civil Police of the Federal District, Brazil, since 2019. In this study, a 4-meter short column gas chromatography-mass spectrometry (GC-MS) qualitative method was optimized and validated to detect cocaine, PAOs (antioxidant 168, FOS; antioxidant 1076, NOX; and butylated hydroxytoluene, BHT) and 16 other cutting agents in cocaine base and salt. NOX and FOS are high-boiling-point compounds that are not amenable to the standard GC-MS methods. The method uses a 250 °C split mode injection, final temperature of 280 °C, and a total run time of 16.5 min. PAOs were found in 84.2% of the 38 cocaine base samples and in 21.5% of the 65 cocaine salt samples (mainly NOX); 20 samples that did not contain any cocaine also contained PAOs (30% NOX and 25% FOS). Other cutting agents found in the samples included phenacetin, aminopyrine, and lidocaine in cocaine base; lidocaine, tetracaine, and caffeine in cocaine salt. This is the first report of PAOs detected as cocaine cutting agents and shows another important application of the short column GC-MS method in forensic science that can also be applied in other areas involving these compounds.