|SOFT - TIAFT 1998||Poster Session 3||Thursday October 8, 1998|
METALDEHYDE DETERMINATION IN BODY FLUIDS BY HEADSPACE SOLID-PHASE MICROEXTRACTION (SPME) AND GAS CHROMATOGRAPHY-MASS SPECTROMETRY IN A CASE OF ACUTE INTOXICATION|
Luciano Tedeschi, Sergio Maietti, Giampietro Frison, Franca Castagna, and Santo Davide Ferrara
Centre of Behavioural and Forensic Toxicology, Institute of Legal Medicine, University of Padova, Via Falloppio 50, I-35121 Padova, Italy
|A 47-year-old woman was admitted to an Intensive Care Unit after attempted suicide by ingestion of a molluscicide containing metaldehyde. On arrival the patient was unconscious, with bilateral reactive mydriasis and tonic-clonic seizures. She was mechanically ventilated after oro-tracheal intubation. Her body temperature rose to 40 °C in the first days of the clinical course, and a status epilepticus also occurred. Among other diagnostic assessments, this laboratory was requested to assay for metaldehyde in blood, urine and dialysis fluid sampled from 12 hours after admission to the 4th day of admission.
A simple, fast and reliable method based on headspace Solid-Phase Microextraction (SPME) and Gas Chromatography-Mass Spectrometry (GC-MS) was developed. SPME was carried out with a 65-µm Carbowax/Divinylbenzene fiber on 0.5-ml-aliquots of each biological fluid, saturated with NaCl and heated at 70 °C for 15 min in sealed vials. GC-MS analysis was performed on a FFAP (acid-modified polyethylene glycol phase) capillary column, in Full Scan acquisition mode (20-250 u.) for identification and Selected Ion Monitoring mode (m/z 89, 117, 131) for quantification. The assay was sufficiently linear over a metaldehyde range of 0.1-200 µg/ml and had a sensitivity of about 0.01 µg/ml for all biological fluids.
Blood and urine metaldehyde levels peaked about 24 hours after admission (10.5 and 18 µg/ml for blood and urine respectively) and were detectable until day 4 (0.6 and 1.3 µg/ml for blood and urine respectively). Dialysis fluid, sampled only on day 4, had very low metaldehyde levels (0.1 µg/ml).
Therapy (barbiturate infusion and haemodialysis) resulted in improvement of the patient's nervous functions. She was extubated on day 7 and discharged on day 9, after her complete recovery.