Detection of Intact Ricin in Crude and Purified Extracts from Castor Beans Using Matrix-Assisted Laser Desorption Ionization Mass Spectrometry

Abstract

Ricin is a highly toxic protein from the seeds of the castor bean plant. Crude extracts from castor beans are toxic by several routes, and there is international concern about the use of these extracts by terrorist organizations. Lethality in aerosolized form has spurred the development of methods for the rapid detection of this protein from air samples that is critical in determining the illicit use of this material. Matrix-assisted laser desorption ionization (MALDI) mass measurement with an automated laser firing sequence was used to detect intact ricin from solutions containing less than 4 microg/mL of ricin in the presence of other endogenous seed proteins. This sensitivity was attained with the addition of 0.01% Tween 80 to the extracts that greatly enhanced the ricin signal. Importantly, this treatment substantially reduces the interference from the castor bean seed storage proteins. Commonly the ricin signal can be completely obscured by the oligomers of seed storage proteins, and this treatment reveals the ricin molecular ion, allowing the analyst to make a judgment as to the ricin content of the extract. This method provides for sensitive and rapid identification of intact ricin from aqueous samples with little sample preparation and is amenable to automatic acquisition.

Ricinus communis Intoxications in Human and Veterinary Medicine—A Summary of Real Cases

“…For unambiguous detection of ricin and its selective discrimination from R. communis agglutinin, sequence information is necessary. Modern state-of-the-art mass spectrometry technologies are able to deliver information on the target’s protein sequence and its glycosylation pattern: highly sophisticated technologies like electrospray ionisation (ESI) or matrix-assisted laser-desorption/ionisation time-of-flight (MALDI-TOF) mass spectrometry (MS) as well as liquid chromatography (LC)-MS/MS analysis of the tryptic peptide fragments have been developed to unequivocally identify ricin out of crude toxin preparations [270,271,272,273,274] and to analyze its glycosylation pattern [118,124]. However, limited sensitivity and the difficulty to identify ricin out of complex matrices lead to the combination of immunoaffinity enrichment with MS-based detection.…”

Characterization of Two Ricin Isoforms by Sodium Dodecyl Sulfate-Capillary Gel Electrophoresis and Capillary Isoelectric Focusing

“…[11][12][13][14][15][16] Among them, CE has received considerable attention because of its ability to separate proteins with high resolution and its applicability of various separation modes, such as sodium dodecyl sulfate-capillary gel electrophoresis (SDS-CGE), capillary isoelectric focusing (CIEF), as well as capillary zone electrophoresis.…”

Rapid Detection of Ricin in Serum Based on Cu-Chelated Magnetic Beads Using Mass Spectrometry

“…It is among the deadliest known poisons with an LD50 in humans of 5-10 μg/kg through inhalation or 350-700 μg for a 70 kg person [3,4]. The ease of production of the toxin from the castor bean seeds and the accessibility of the plants in several countries have led ricin to be considered a biological weapons by the US Centers for Disease Control and Prevention (CDC) [3,5,6].…”