Detection of anticoagulant residues by a new HPLC method in specimens of poisoned animals and a poison control case study.

Poisonings of domestic and wildlife animals are frequently caused by anticoagulants. Between 1996 and 2003, 70% of all suspected animal poisoning cases were confirmed in this laboratory following analysis of a variety of specimens. Thirty-nine percent of all animal poisonings detected in this laboratory were caused by anticoagulants. Suspicious veterinarians and pet owners involved with animal poisonings ask for toxicological analyses. With respect to these demands, a new high-performance liquid chromatography (HPLC) method (system-I, reversed-phase C-18 column, methanol/ammonium acetate) combined with specific extraction procedures was developed for the sensitive detection of nine substances with anticoagulative properties. This method yields high recoveries of the analytes, which can simultaneously be detected. In addition, another HPLC (system-II, acetonitrile/potassium phosphate) was used to confirm and separate chromatographic peaks, which could not be resolved by HPLC system-I. The reliable method has good reproducibility and is most suitable for forensic analyses. Using these analytical procedures, concentrations of eight organic anticoagulants were determined in more than 100 aliquots of animal liver, blood, bait, gastric content, bloody intestinal content, and water. Over the last eight years, dogs and wild birds were the most frequently poisoned species. Interestingly, lethally poisoned birds had lower anticoagulant residues in their organs than mammals.

The isomeric metabolites of doxepin in equine serum and urine.

Due to its tranquilizing properties, the tricyclic antidepressant doxepin may be misused as a doping agent in competition horses. Therefore, efficient analytical procedures are required to detect this drug in samples submitted for doping control. To screen for parent doxepin in equine blood and urine, a less specific method has been accepted employing gas chromatography (GC) combined with electron impact (EI) mass spectrometry (MS). The aim of this study was identification of doxepin metabolites providing more specific MS data to verify positives resulting from screening. Thus, after a horse was given doxepin-HCl (1 mg/kg, i.v.), blood and urine were analyzed for free or conjugated metabolites using GC combined with EI- and positive chemical ionization (PCI) MS. In both of the sample materials, cis- and trans-isomers of desmethyldoxepin were detected for up to 48 h after treatment using trifluoracetylation and GC/EI-MS. Following enzymic hydrolysis of urine and propionylation of extracts, each four isomers of hydroxy desmethyldoxepin and hydroxydoxepin were recovered for up to 24 and 48 h, respectively. These compounds were characterized by their EI- and PCI-mass spectra. Although distinct positions of the hydroxyl groups could not be determined, the presence of each two cis/trans-isomeric pairs of differently monohydroxylated metabolites may be assumed. Results reported here suggest, that screening horses for parent doxepin should be completed by analysis of its major isomeric metabolites, desmethyldoxepin and hydroxydoxepin, providing MS data specific enough for confirmatory analysis.