Forensic Science International 110 (2000) 145–152 www.elsevier.com / locate / forsciint Analytical method for the determination of strychnine in tissues by gas chromatography / mass spectrometry: two case reports a, b a a a * E.P. Marques , F. Gil , P. Proenc ¸a , P. Monsanto , M.F. Oliveira , a a A. Castanheira , D.N. Vieira a ´ Laboratorio de Toxicologia Forense, Instituto de Medicina Legal de Coimbra, Faculdade de Medicina da Universidade de Coimbra, Coimbra, Portugal b ´ Departamento de Medicina Legal y Psiquiatrıa, Facultad de Medicina, Universidad de Granada, Granada, Spain Received 19 January 1999; received in revised form 18 January 2000; accepted 24 January 2000 Abstract This paper describes an analytical method for strychnine determination in biological samples by gas chromatography / mass spectrometry and their application in the investigation of two cases involving strychnine ingestion: A fatal case and a clinical one. The strychnine is isolated from biological samples using a liquid–liquid extraction procedure. The clean-up procedure is performed using an acid solution. Papaverine is used as internal standard in the quantification of strychnine. In the analysed specimens, the limits of quantification were 0.1 mg/ml or 0.1 mg/g. The recovery rate ranged from 75.0% to 98.7% and the coefficients of variation ranged from 4.8% to 10.5%.  2000 Elsevier Science Ireland Ltd. All rights reserved. Keywords: Strychnine; Rodenticide; Alkaloid; GC / MS 1. Introduction Strychnine is an alkaloid which is mainly extracted from the seeds of Strychnos nux vomica, a tree native to India. This compound is highly toxic to humans. It is rapidly *Corresponding author. Tel.: 1351-239-854-230; fax: 1351-239-820-549. E-mail address: imltoxic@.ci.uc.pt (E.P. Marques) 0379-0738 / 00 / $ – see front matter  2000 Elsevier Science Ireland Ltd. All rights reserved. PII: S0379-0738(00)00153-5