Forensic Determination of Ricin and the Alkaloid Marker Ricinine From Castor Bean Extracts

Abstract Liquid chromatography/mass spectrometry (LC/MS) and matrix assisted laser desorption/ionization time-of-flight (MALDI-TOF) MS methods were developed for the presumptive identification of ricin toxin and the alkaloid marker ricinine from crude plant materials. Ricin is an extremely potent poison, which is of forensic interest due to its appearance in terrorism literature and its potential for use as a homicide agent. Difficulties arise in attempting to analyze ricin because it is a large heterogeneous protein with glycosylation. The general protein identification scheme developed uses LC/MS or MALDI-TOF for size classification followed by the use of the same instrumentation for the analysis of the tryptic digest. Fragments of the digest can be searched in an online database for tentative identification of the unknown protein and then followed by comparison to authentic reference materials. LC fractionation or molecular weight cutoff filtration was used for preparation of the intact toxin before analysis. Extracts from two types of castor beans were prepared using a terrorist handbook procedure and determined to contain 1% ricin. Additionally, a forensic sample suspected to contain ricin was analyzed using the presented identification scheme (data not shown). The identification of the alkaloid ricinine by GC/MS and LC/MS was shown to be a complementary technique for the determination of castor bean extracts.