Analysis of ricinine and L-abrine for screening of beverage samples contaminated by castor beans and rosary peas

Abstract

Protein toxins are toxic proteins produced by animals, plants, or microbes. Ricin and abrin are highly toxic protein toxins contained in plants seeds, castor beans (Ricinus communis) and rosary peas (Abrus precatorius), respectively. Ricin is also classified as a chemical warfare agent and restricted internationally by the Chemical Weapons Convention. Although those toxins with high purity are difficult to produce or obtain by ordinary people, the plants seeds are easy to obtain because those seeds are used in industry or used for gardening or accessories. Thus, murder attempts by contaminating those seeds into a beverage have occurred. To confirm the use of these seeds, the analysis of protein toxins themselves by biochemical methods are required. Nevertheless, those analyses are complicated and not easily implemented by scientists who are usually involved in the analysis of small molecules such as illicit drugs and poisons. On the other hand, small alkaloids ricinine and L-abrine are contained in castor beans and rosary peas, respectively. If analytical methods of those small molecules are used for the suspicious beverage sample initially, scientists can determine whether to proceed to the analysis of protein toxins or not. For biological samples, screening methods of ricin or abrin exposure by detecting ricinine or L-abrine have been reported by some groups. However, simultaneous screening method for beverage samples have not been reported so far. In this work, we have developed simultaneous LC-MS/MS method of ricinine and L-abrine using a phenyl column and applied the optimized method to beverage samples. After simple pretreatments involving deproteinization and solid phase extraction, ricinine and L-abrine could be detected at low concentration and the quantitation results were also sufficient for screening purpose. The method was also applied to beverage samples contaminated with castor beans, and applicability to real samples was confirmed.