Background: Haloperidol, 4-[4-(4-chlorophenyl)-4-hydroxy-1-piperidinyl]-1-(4-fluorophenyl)-1-butanone (HP), one of the most widely used antipsychotics in the treatment of schizophrenia, mania, and other psychiatric disorders, is frequently encountered in cases of unintentional pediatric intoxication because the ingestion of a small amount can cause significant toxic effects in children. For monitoring HP in suspected ingestions, a liquid chromatography-high-resolution mass spectrometry method has been developed and validated in urine, blood, and hair samples.
Methods: The analyte was extracted from 1 mL blood or urine by liquid/liquid extraction and from 5 mg of hair by micropulverized extraction; gradient elution on an Atlantis T3 column was realized using HP-d4 as an internal standard. Positive ion electrospray ionization and high-resolution mass spectrometry determination were performed in an Orbitrap mass spectrometer.
Results: The method exhibited a r > 0.999 in the studied ranges (0.1-50 ng/mL in urine and blood and 0.1-50 ng/mg in hair) and a limit of quantification of 0.1 ng/mL for urine and blood and 0.1 ng/mg for hair; intra-assay and interassay relative SDs were always more than 18%. The method was applied to determine haloperidol in 3 children who were admitted to emergency departments. HP concentrations ranged from 2 to 21 ng/mL in urine, from not detected to 4.9 ng/mL in blood, and from 0.37 to 0.73 ng/mg in hair samples.
Conclusions: The utilization of high-resolution/high-accuracy mass spectrometry in full scan mode allowed the identification of HP metabolites in urine and blood, thus unequivocally documenting the exposure to the drug. HP metabolites were structurally characterized by high-resolution multiple mass spectrometry. For the first time, a HP metabolite was detected in hair.