Trace isotope analysis of Ricinus communis seed core for provenance determination by laser ablation-ICP-MS

Abstract

The castor bean plant, Ricinus communis, grows wild throughout many regions of Australia. The seeds of the plant contain the schedule 1 chemical agent ricin, a type II ribosomal inhibiting protein. Currently there are limited analytical techniques that can be applied in analysis of the seeds to establish attribution. In this study, laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) was used for the analysis of seeds collected from 68 plants across 38 locations around Australia. Of the 92 elemental isotopes measured, fifteen (²⁴Mg, ²⁷Al, ⁴⁴Ca, ⁵³Cr, ⁵⁵Mn, ⁵⁷Fe, ⁶⁰Ni, ⁶⁵Cu, ⁶⁶Zn, ⁷⁵As, ⁸⁵Rb, ⁸⁸Sr, ⁹⁸Mo, ¹³⁸Ba and ²⁰²Hg) yielded data that were relevant to all collection sites. Data were further analysed using multivariate statistical analysis which facilitated the potential for the identification of unique provenance isotopes. Furthermore, this analysis indicated that ⁵⁹Co was present at significant levels in Victorian and Sydney specimens only.

Keywords: Laser ablation-ICP-MS; Multivariate statistical analysis; Provenance; Ricin; Ricinus communis; Trace isotope.