From Bench to Bedside: Validation of an ELISA Analytical Method for the Determination of Ricin in Biological Samples and Clinical Data on Related Intoxications

Accidental and deliberate poisoning by Ricinus communis, a wild plant cultivated for castor oil, has been known for centuries. Seeds contain one of the deadliest known plant toxins, ricin, along with its dimer RCA120. Due to its toxicity and ease of extraction, ricin poses a potential threat as a chemical weapon, highlighting the need for reliable laboratory detection. In this work, ricin and RCA120 (Ricinus communis agglutinin) were extracted from castor beans and purified by solid-phase extraction (SPE) and Gel Permeation Chromatography (GPC). Purity was confirmed through Sodium Dodecyl Sulphate-PolyAcrylamide Gel Electrophoresis (SDS-PAGE). Then, lab-made standards were used to validate an Enzyme Linked ImmunoSorbent Assay (ELISA) kit to identify ricin in biological matrices after SPE extraction. Parallelly, SDS-PAGE was used to qualitatively confirm the presence of toxins. The developed method demonstrated a detection limit (LOD) of 2.74 ng/mL and was used to analyse biological specimens of seven human intoxication cases managed by Pavia Poison Control Centre (PCC). This study provides a quiet, inexpensive protocol that within 5 h allows the screening of potential ricin-exposure victims. Its implementation in clinical laboratories could support the management of intoxicated patients, ensuring faster and more accurate clinical response.