Gas chromatography-tandem mass spectrometric analysis of metaldehyde and its metabolite acetaldehyde in initial assessment of hemodialysis abatement of toxicity in live animals.

Metaldehyde consumption by pets and other mammals constitute medical emergencies ideally requiring rapid poison removal. The purpose of this study was three-fold: 1) development of a sensitive method for metaldehyde quantitation in patient serum samples by gas chromatography combined with tandem quadrupole mass spectrometry (GC/MS/MS); 2) development of a sensitive method for quantitation of the volatile metaldehyde metabolite acetaldehyde by headspace analysis combined with GC/MS/MS; and 3) an initial assessment of the efficacy of combined dialysis and hemoperfusion treatments in diminishing toxin loads in canine victims of metaldehyde poisoning. Both mass spectrometric approaches relied on Multiple Reaction Monitoring (MRM) methodologies. Metaldehyde extracted via liquid-liquid partitioning from serum was detected with a limit of quantitation (LOQ) of 7.3 ± 1.4 ng/mL with linearity in the range 1-250 ng/mL with accuracy improved by inclusion of a deuterated metaldehyde internal standard. Acetaldehyde was determined to have an LOQ of 0.39 μg/mL with linearity in the range 1-1000 μg/mL. The developed methodologies were applied to canine samples taken over various time points during dialysis treatment. Two of three canine patients showed significant abatement of metaldehyde levels by over 50-fold from initial concentrations while a third was shown to be negative with no measureable metaldehyde. The toxic metabolite acetaldehyde was found in one of the metaldehyde-poisoned patients and the detected acetaldehyde was also reduced by roughly 200-fold during the course of treatment. The designed mass spectrometric techniques were thus successful in demonstrating the efficacy of the applied dialysis-hemoperfusion methods which may find wider applicability against other potentially lethal toxins in poisoned patients in future studies.