Determination of strychnine in human blood using solid-phase extraction and GC-EI-MS

A rapid, simple, and sensitive method has been developed for the identification and quantitation of strychnine in human blood. The sample cleanup procedure involved solid-phase extraction with Oasis(R) HLB cartridges. The extracts were analyzed by gas chromatography-electron impact ionization-mass spectrometry. Limits of detection (LOD) and quantitation (LOQ) were 0.03 and 0.10 microg/mL, respectively, and the method was found to be linear between the LOQ and 2.5 microg/mL, with a correlation coefficient of 0.9994. Intra- and interday precision and accuracy were determined at both low and high concentrations (0.50 and 2.00 microg/mL). The CVs ranged from 5.63 to 8.50% and bias was within +/- 10% of the true value. Mean recovery of strychnine was 90.7%. Because of its simplicity and speed, the described method can be applied in forensic toxicology laboratories to determine this alkaloid in whole blood samples. Also, the fact that only 0.5 mL of blood is required to accomplish the analysis make this procedure useful in situations where several exams are needed and the sample volume is limited.