Metaldehyde, a widely used molluscicide, is the third cause of intoxication by pesticides in domestic animals in Europe. Most mammalian species are susceptible, and its exposure may lead to death within a few hours. While metaldehyde intoxication diagnosis is in most cases presumptive, based on the symptomatology or from "postmortem" analysis, few analytical methods are currently available for live animals. The aim of this work was to describe a fast analytical method for the specific and quantitative determination of metaldehyde in animal whole blood and serum at concentrations of toxicological significance. A liquid-liquid extraction with chloroform and gas chromatography-mass spectrometry quantification are proposed. The method limit of quantification (LOQ) was 0.04 µg/mL in serum and whole blood. The method was linear in the range from 0.04 to 200 µg/mL. The recovery was between 93% and 102% for LOQ, low, medium and high spike concentrations. Intra- and inter-assay relative standard deviation was <12% in all spike concentrations in both serum and whole blood, apart from one of the experiments at LOQ in whole blood, which accounted for 17.7%. The method was applied to real intoxication cases, and the concentration found in positive samples was between 29 and 69 µg/mL. The proposed method provides high sensitivity, accuracy and precision and can be used to assist in the diagnosis of metaldehyde poisoning.
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