Determination of Brodifacoum by Gas Chromatography Coupled to Mass Spectrometry: A New Analytical Methodology for the Determination of Coumarin Rodenticides in Poisoned Foods

The use of efficient and reliable methods is extremely important for analyzing food samples suspected of containing toxic substances. Due to the difficulty in obtaining highly toxic illicit poisons of the carbamate type (aldicarb/carbofuran) and organophosphates (terbufos), popularly known as chumbinho, which were banned by Agência Nacional de Vigilância Sanitária (ANVISA), there is an increase in cases of suicide and attempted murder using another type of poison: commercial coumarin rodenticides based on brodifacoum which are freely sold in pesticide product stores. The low concentration of the active ingredient (0.005%, m/m) in formulated products containing coumarins makes it difficult to identify these substances in samples with a small amount of poison or when mixed in food, requiring more complex extraction methodologies and instrumentation that many forensic investigations do not have, often generating inconclusive reports. In this work we studied a new analytical methodology for the extraction and identification of brodifacoum, one of the coumarins commonly found in these poisons, using gas chromatography coupled with mass spectrometry (GCMS). In extraction by sonification, we use acetone and methanol/formic acid 50:1 as extracting solvents, followed by concentration and subsequent analysis by chromatography, obtaining excellent results in identifying the main degradation product of brodifacoum in the formulated products, even when mixed with food in cases of poisoning, relating its concentration to that of the commercial standard. This work provides an alternative method of analyzing these materials, helping scientific police prepare more conclusive reports in cases of coumarin poisoning, thus reducing impunity.