Determination of Aldicarb, Carbofuran and Methamidophos in Blood Derived from Forensic Cases through Liquid Chromatography with Electrospray Ionization and Tandem Mass Spectrometry (LC-ESI-MS/MS)

Abstract

Abstract The presence and use of carbamate and organophosphate pesticides with agricultural and urban purposes in Colombia has been justified for pest control. However, these substances pose a national problem because of their toxic nature, which is associated with accidental poisoning or even with homicides or suicides related to acute fatal poisoning. This study aims to develop and to validate an analytical methodology for the determination of the aldicarb, carbofuran and methamidophos pesticides in blood through liquid chromatography tandem mass spectrometry (LC–MS-MS). To this end, the method for extracting pesticides from the blood was developed, the conditions of LC were defined, the instrumental system MS-MS was optimized and the bioanalytical methodology was validated. This methodology proved to be selective, precise, accurate and linear in the concentration range from 0.10 to 5.0 µg/mL, with a limit of detection of 0.020 µg/mL for aldicarb and carbofuran and 0.050 µg/mL for methamidophos, recovery between 90% and 102%, and stability at room temperature and in the autosampler between 80% and 120%. The analytical methodology was applied to 34 forensic cases. Carbofuran was found at a concentration ranging from 0.020 to >5.0 µg/mL, aldicarb was found at a concentration ranging from 0.10 to 2.5 µg/mL and methamidophos was found at a concentration >5.0 µg/mL. In 62% of the cases, the pesticides under study were used to commit suicide. Necropsy findings of pesticide poisoning are non-specific. Therefore, toxicological blood analysis provides significant information at the forensic level, and the analytical method validated represents a sensitive, fast and reliable analysis with little solvent consumption of a small sample amount, so it is suitable for routine application in fatal pesticide poisonings.