Application to several suspected poisoning cases of a validated analytical method for the determination of muscarine in human biological matrices using liquid chromatography with high-resolution mass spectrometry detection

Despite prevention efforts, many cases of mushroom poisoning are reported around the world every year. Among the different toxins implicated in these poisonings, muscarine may induce parasympathetic neurological damage. Muscarine poisonings are poorly reported in the current literature, implying a lack of available data on muscarine concentrations in human matrices. A validated liquid chromatography with high-resolution mass spectrometry detection (Orbitrap technology) method was developed to determine muscarine concentrations in human urine, plasma, and whole blood samples. Muscarine was determined using 100 μL of biological fluids, and precipitation was used for sample preparation. Liquid chromatography-mass spectrometry was performed using an Accucore Phenyl-X analytical column with the electrospray source in positive ion mode. Muscarine was quantitated in parallel reaction monitoring (PRM) mode with D9-muscarine as the internal standard. The method was validated successfully over the concentration range 0.1-100 μg/L for plasma and whole blood and 1-100 μg/L for urine, with acceptable precision and accuracy (<13.5%), including the lower limit of quantification. Ten real cases of suspected muscarine poisoning were successfully confirmed with this validated method. Muscarine concentrations in these cases ranged from 0.12 to 14 μg/L in whole blood, <LOQ to 43 μg/L in plasma, and <LOQ to 1537 μg/L in urine. This work provides a tool of choice for the diagnosis of muscarine poisoning when mushrooms are not available for identification, as well as the possibility of determining toxins in the blood, which is an important step toward understanding the pharmacokinetics of the mycotoxin.