Investigating Rodenticide Poisoning Using LC–MS/MS

Researchers from Hannover, Germany, have developed a liquid chromatography–tandem mass spectrometry (LC–MS/MS) multi-target screening strategy for use in ante-mortem and post-mortem rodenticide analysis in forensic toxicology (1).

Rodenticides are a commonly used method of controlling rodent populations. However, these substances also pose significant risk to domestic animals such as cats and dogs because secondary poisoning might occur if the baited traps or poisoned rodent is ingested. Furthermore, human poisoning with rodenticides does occur and a reliable and convenient identification methodology for the relevant substances is essential for forensic toxicology laboratories.

There are numerous classes of rodenticides and their analysis is performed predominately using LC–MS/MS. While these methods are successful, they only focus on rodenticides and do not allow the simultaneous identification of other substances, which is useful for confirming a suspected rodenticide poisoning but not as useful if the case history is unclear and a wider forensic toxicology net is required. Additionally, a common issue encountered in forensic toxicology is a lack of the relevant analytical material available, which can make the use of multiple investigatory analyses unviable. Therefore, a method that can reduce the number of required analyses and cover the most important substances in relevant concentration ranges is required.

In this paper, researchers aimed to develop a multi-target screening strategy based on a simple and fast sample preparation step and test it by investigating real cases of rodenticide toxications in animals. The developed method utilized a simple protein precipitation step for sample preparation and LC–MS/MS, targeting multiple rodenticides, including: α-chloralose, brodifacoum, bromadiolone, coumatetralyl, difenacoum, and warfarin. In total, around 250 substances are covered by the method, which was validated to ensure the substances could be identified at low concentration ranges. Further to the rodenticides, the method was also capable of identifying common drugs regularly screened for in forensic toxicology.

While the method was developed for human plasma and post-mortem blood, it can also be utilized for animal testing, with real animal samples from dogs and cats suspected of eating rodenticide baits being investigated. In the processed cases, all rodenticides were identified except for bromadiolone.

The presented method offered several advantages over current analytical procedures, and the researchers believe there is scope for future development of the method with the incorporation of rodenticide-related metabolites, which could give additional information and help in the interpretation of investigated intoxications.

Reference

1. A. Arens et al., Drug Test Anal. 14, 1149–1154 (2022). DOI: 10.1002/dta.3222